^_n_n_-n, 


REESE  LIBRARY 


UNIVERSITY  OF  CALIFORNIA. 

'Kfceiiied  ,190    . 

Accession  No.      82891     •   Class  No. 


ENG-INE    TESTS 


EMBRACING   THE    RESULTS   OF   OVER    ONE    HUNDRED 
FEED-WATER  TESTS  AND   OTHER   INVESTIGA- 
TIONS  ON   VARIOUS   KINDS   OF   STEAM 
ENGINES,    CONDUCTED   BY 
THE  AUTHOR, 


BY 


GEO.  H.  BABKUS,  S.B. 

« t 

MEMBER    OF    AMERICAN    SOCIETY    OF    MECHANICAL    ENGINEERS,   BOSTON 

SOCIETY    OF    CIVIL    ENGINEERS,  NEW    ENGLAND 

WATER-WORKS    ASSOCIATION. 


NEW    YORK: 

D.  VAN    NOSTRAND    COMPANY 
1900 


COPVKIGHT,   1900,   BY 

GEO.    H.    BAEKUS. 


PREFACE. 


THE  favor  with  which  the  author's  book  on  "  Boiler  Tests," 
published  in  1891,  has  been  received,  has  led  him  to  collect  in 
similar  form  the  data  and  results  obtained  on  many  of  his 
engine  tests.  Some  of  the  tables  of  results  have  appeared 
from  time  -to  time  in  mechanical  journals  and  in  pamphlets ; 
also  in  the  Transactions  of  the  American  Society  of  Mechanical 
Engineers,  but  a  large  part  is  now  printed  for  the  first  time. 

It  is  believed  that  the  data  here  presented  will  prove  of 
value  to  the  engineering  profession,  to  owners  and  intending, 
purchasers  of  steam  plants,  and  to  any  who  are  interested  in 
the  economical  production  of  power.  The  book  should  be  of 
special  value  to  engineers  advising  intending  purchasers  of 
engines,  on  account  of  the  assistance  it  will  render  in  making 

a  wise  selection. 

GEO.    H.  BARRUS. 

95  MILK  STRKET,  BOSTON,  March,  1900. 

3 


82891 


CONTENTS. 


PART   I. 

PAGE 

INTRODUCTION 9 

How  THE  FEED-WATER  TESTS  WERE  CONDUCTED 12 

MEASUREMENT  OF  THE  FEED-WATER 13 

INDICATING 18 

GENERAL  METHOD  OF  CARRYING  ON  THE  FEED-WATER  TEST  ....  21 

LEAKAGE  TESTS  OF  VALVES  AND  PISTONS 23 

CALIBRATION  OF  INSTRUMENTS 28 

MANNER  OF  WORKING  UP  THE  TESTS 30 

TABLE  OF     1875°  39 
m.  e.  p. 

PART   II. 

FEED-WATER  TESTS  OF  SIMPLE  ENGINES 43 

FEED-WATER  TESTS  OF  COMPOUND  ENGINES 131 

FEED-WATER  TESTS  OF  TRIPLE  EXPANSION  ENGINES 235 

SUMMARY  OF  FEED-WATER  TESTS 245 

REVIEW  OF  FEED-WATER  TESTS fc     ,  249 

I.     CYLINDER  CONDENSATION  AND  LEAKAGE ;  .     .  251 

II.     EFFECT  OF  PRESSURE  ON  THE  ECONOMY 258 

III.  EFFECT  OF  SPEED  UPON  ECONOMY 259 

IV.  ECONOMY  OF  CONDENSING 261 

V.     EFFECT  OF  SUPERHEATING ....  265 

VI.      RELATIVE    ECONOMY    OF   SIMPLE,  COMPOUND,    AND   TRIPLE    EX- 
PANSION ENGINES 267 

VII.     ECONOMY  OF  STEAM-JACKETING  AND  RE-HEATING  IN    COMPOUND 

ENGINES  „ 270 

VIII.     EFFECT  OF  RATIO  OF  CYLINDER  AREAS  IN    COMPOUND  ENGINES,  273 

IX.      MISCELLANEOUS 274 

VALVE  SETTING .  279 

STEAM-PIPE  DIAGRAMS    .  321 


PART    I. 


ENGINE  TESTS, 


INTRODUCTION. 

THE  first  work  in  the  line  of  engine-testing  with  which  the 
author  was  intimately  connected  was  carried  out  at  the  Massa- 
chusetts Institute  of  Technology  in  the  years  1875  to  1878. 
During  this  time  he  was  engaged  in  conducting  the  experi- 
ments of  the  late  George  B.  Dixwell  on  the  use  of  superheated 
steam  for  motive  power.  ,  The  experiments  consisted  princi- 
pally in  investigations  on  a  Corliss  engine  operated  with  both 
saturated  and  superheated  steam  ;  and  they  embraced  the  deter- 
mination of  the  performance  of  the  engine  running  under  both 
of  these  conditions  with  different  points  of  cut-off,  and  with 
different  degrees  of  superheating,  together  with  the  determina- 
tion of  the  effect  of  other  changes  in  the  conditions  of  opera- 
tion. The  engine  in  question,  and  the  testing  apparatus 
connected  with  it,  formed  the  nucleus  of  a  mechanical  labora- 
tory used  in  instructing  the  students  of  the  Institute ;  and  it 
was  the  first  of  the  many  steam  laboratories  which  have  been 
established  in  the  colleges  of  this  country.  In  the  course  of 
these  investigations  a  board  of  experts,  consisting  of  Chief 
Engineers  Loring,  Baker,  and  Farmer  of  the  United  States 
Navy,  was  appointed  by  the  Bureau  of  Steam  Engineering  to 
examine  the  subject;  and  they  conducted  a  series  of  tests  on 
the  same  plant,  and  reported  them  to  the  Bureau.  These  trials 
were  under  the  active  charge  of  the  author.  The  character  of 
this  work  was  such  as  to  require  from  the  very  first  the  most 
reliable  apparatus  and  the  best  methods  and  instruments.  In 
preparing  for  it  and  carrying  it  on,  the  author  had  the  best 


10  ENGINE    TESTS. 

opportunity  that  could  be  afforded  at  that  time  for  becoming 
educated  in  the  practice  of  engine-testing,  and  the  training 
thus  acquired  laid  the  foundation  for  much  of  the  testing-work 
in  which  he  has  since  been  engaged. 

This  volume  relates  mainly  to  the  engine  tests  which  the 
author  has  conducted  subsequent  to  the  investigations  in  super- 
heating just  referred  to.  It  has  been  his  custom,  whenever  en- 
gaged upon  any  work  relating  to  the  performance  of  engines, 
to  advocate  the  determination  of  their  economy  on  the  basis  of 
feed-water  consumption,  rather  than  on  that  of  the  coal  con- 
sumed. Whenever  called  upon  simply  for  indicating,  he  has 
advocated  the  feed-water  test,  rather  than  to  rely  solely  on  the 
showing  of  the  diagram.  In  a  great  many  instances  the  feed- 
water  test  has  thus  been  undertaken  where  it  would  have  other- 
wise been  omitted.  By  following  this  practice,  and  answering 
the  calls  which  have  come  in  the  ordinary  course,  the  author 
has  personally  obtained  a  considerable  amount  of  data,  which 
he  believes  to  be  of  value  to  the  engineering  public,  as  well  as 
to  all  who  are  interested  in  the  use  of  power  or  development  of 
economical  engines,  and  therefore  worthy  of  publication  in 
permanent  form,  as  here  presented. 

The  author's  work  in  engine-testing  has  embraced  the  indi- 
cating of  engines  for  the  simple  purpose  of  valve-setting ; 
indicating  for  the  determination  of  the  horse-power,  or  for 
determining  the  power  used  by  various  machines  or  depart- 
ments of  machinery  which  the  engine  drives ;  investigations 
upon  the  economy  of  different  systems  of  operating  engines ; 
feed-water  tests  having  for  an  object  the  improvement  of  the 
engine  and  the  attainment  of  greater  economy ;  and  tests  having 
in  view  the  determination  of  the  fulfilment  or  non-fulfilment  of 
the  terms  of  a  contract  guaranteeing  a  certain  efficiency.  These 
investigations  and  tests  have  been  made  on  a  great  variety  of 
engines,  from  the  simple  non-condensing  engine  with  a  single 
cylinder,  to  the  triple  expansion  condensing  engine ;  and  they 
relate  to  many  designs  and  to  products  of  many  builders.  They 
have  also  covered  widely  varying  conditions  of  service  as  to 
boiler  pressure,  cut-off,  load,  speed,  and  valve-setting,  together 


INTRODUCTION.  11 

with  various  conditions  in  regard  to  quality  of  steam,  use  of 
jackets,  and  the  tightness  of  valves  and  pistons. 

The  tests  reported  in  this  volume  have  not  been  made  with 
an  organized  attempt  to  obtain  the  performance  of  certain  types 
and  makes  of  engines ;  but  they  are  the  result  of  the  investiga- 
tions which  the  author  has  made  in  responding  to  the  calls  of 
his  clients,  whether  it  happened  to  be  for  one  object  or  another, 
and  whatever  the  class  of  engine  or  conditions  of  service.  So 
far  as  given  here  they  are  confined  mainly  to  stationary  engines 
located  in  manufacturing  establishments,  and  in  most  cases 
operating  with  a  fairly  uniform  load.  Nearly  all  the  tests  apply 
to  engines  which  have  a  capacity  of  at  least  100  horse-power, 
and  they  run  from  this  size  up  to  1700  horse-power. 

The  first  part  of  the  volume  is  devoted  to  Feed-Water  Tests, 
taking  up  first  the  simple  engine,  both  condensing  and  non- 
condensing,  and  afterwards  compound,  and  triple-expansion 
engines.  The  results  of  the  test  on  each  engine  are  given  in  a 
table  by  itself,  and  they  .are  presented  in  such  detail  that  all 
necessary  information  regarding  the  subject  is  at  hand.  In 
connection  with  the  results  is  given  in  each  case  the  dimensions 
and  such  information  regarding  the  design  of  the  engine,  the 
conditions  under  which  it  was  worked,  and  the  character  of  the 
test,  as  is  needed  for  a  clear  understanding  of  each  case  ;  and 
comments  on  the  results  are  added  where  these  are  required. 
In  all  the  engines  the  condition  of  the  valves  and  pistons  as  to 
leakage  is  pointed  out  so  far  as  this  can  be  expressed  in  general 
terms.  The  engines  selected  were,  as  a  rule,  fairly  tight ;  but 
in  a  few  cases  tests  of  leaking  engines  are  introduced,  either  on 
account  of  the  general  interest  attaching  to  them,  or  to  show 
the  wasteful  effect  of  the  leakage  itself  in  some  special  instance. 
The  tables  of  feed-water  tests  are  followed  by  a  chapter  which 
presents  a  general  review  of  the  results,  showing  in  brief  the 
main  points  of  information  which  the  tests  bring  out.  This 
chapter  takes  up  the  question  of  cylinder  condensation,  and 
analyzes  the  tests  here  reported,  with  the  object  of  determining 
what  the  percentage  of  cylinder  condensation  under  different 
conditions  of  running  practically  amounts  to.  The  relative 


12  ENGINE    TESTS. 

economy  of  simple,  compound,  and  triple-expansion  engines  is 
considered,  also  the  effects  of  superheating,  jacketing,  and  piston 
speed,  so  far  as  the  tests  furnish  data  on  these  subjects. 

The  chapters  on  Feed-Water  Tests  are  followed  by  one  de- 
voted to  Valve-Setting  and  Effects  produced  by  various  condi- 
tions of  operation,  as  illustrated  by  diagrams  which  the  author 
has  taken  in  his  professional  work.  The  final  chapter  relates 
to  Steam-Pipe  Diagrams. 

In  connection  with  the  matter  relating  to  each  engine, 
whether  feed-water  tests,  valve-setting,  or  otherwise,  sample  in- 
dicator diagrams  are  presented,  usually  reproduced  three-fourths 
size,  showing,  so  far  as  possible,  average  conditions.  In  the 
case  of  feed- water  tests,  diagrams  are  given  from  both  ends  of 
the  cylinders ;  but  in  cases  of  valve-setting  and  miscellaneous 
diagrams,  the  diagrams  shown  are,  as  a  rule,  from  only  one  end 
of  the  cylinder. 


HOW    THE    FEED-WATER    TESTS    WERE 
CONDUCTED. 

Before  presenting  the  individual  feed-water  tests,  and  the 
review  of  the  same  as  noted,  it  is  proper  to  give  a  description  of 
the  methods  employed  in  conducting  them.  This  description 
is  of  a  general  character,  applying  rather  to  the  usual  prac- 
tice of  the  author  in  conducting  these  and  other  engine  tests 
than  to  each  individual  trial  reported  here.  The  principles,  how- 
ever, are  applicable  to  the  individual  tests  quite  as  much  as  to 
the  tests  as  a  whole.  In  the  form  thus  presented,  not  only  are 
the  methods  employed  in  conducting  these  tests  described,  but 
methods  which  should  be  adopted  in  the  general  work  of  test- 
ing, so  far  as  they  accord  with  the  author's  experience. 

The  two  essential  quantities  to  be  determined  in  conducting  a 
feed-water  test  are  the  weight  of  feed-water  consumed,  and  the 
indicated  horse-power  developed  in  the  cylinder. 


HOW    THE    THE    TESTS    WERE    CONDUCTED.  13 


MEASUREMENT    OF    THE    FEED-WATER. 

How  the  feed-water  should  be  measured  is  a  matter  which 
depends  somewhat  upon  the  arrangement  of  the  plant  and  the 
type  of  apparatus  used  for  feeding  the  boilers,  and  this  must  in 
a  great  many  cases  be  adapted  to  the  local  conditions.  It  is 
always  best  to  weigh  the  water,  and  for  this  purpose  to  erect 
tanks  and  scales  suitable  for  the  work.  There  are  instances, 
however,  where  it  is  impossible  to  do  this,  because  it  is  neces- 
sary that  water  should  be  available  under  some  head  so  as  to  fill 
the  weighing-tank,  which  is  generally  elevated  several  feet 
above  the  pump ;  and  there  are  cases  where  no  water  is  at  hand 
under  the  necessary  head.  A  meter  can  be  employed  in  such 
cases,  or  the  water  may  be  supplied  through  an  orifice  of  known 
size  arranged  so  as  to  be  calibrated.  In  most  cases,  however, 
the  system  of  measurement  by  weighing  can  be  employed ;  and 
wherever  it  can  be  done,  the  method  is  to  be  followed  in  prefer- 
ence to  all  others.  The  simplest  apparatus  of  this  kind,  having 
a  capacity  of  say  6,000  Ibs.  of  water  per  hour,  consists  of  a 
small  hogshead  connected  to  the  suction-pipe  of  the  pump  or 
injector,  and  an  ordinary  oil-barrel  mounted  on  platform  scales, 
the  latter  being  supported  by  the  hogshead  on  one  side  and  by 
a  suitable  staging  on  the  other  side.  The  barrel  is  filled  by 
means  of  a  cold-water  pipe  leading  from  the  source  of  supply, 
and  this  should  be  1-J-"  pipe  for  pressures  not  less  than  25  Ibs. 
The  outlet  valve  of  the  barrel  is  attached  to  the  side  close  to 
the  bottom,  and  this  should  be  at  least  2£"  in  diameter  for  quick 
emptying.  Where  larger  quantities  of  water  are  required,  the 
barrel  can  be  replaced  by  a  hogshead,  and  two  additional  hogs- 
heads can  be  coupled  together  for  the  lower  reservoir.  The 
capacity  reached  by  this  arrangement  when  the  weighing  hogs- 
head is  supplied  through  a  2£"  valve  under  25  Ibs.  pressure, 
and  emptied  through  a  5"  valve,  is  15,000  Ibs.  of  water  per 
hour.  For  still  larger  capacity  it  is  desirable  to  use  rectangular 
tanks  made  for  the  purpose,  and  have  the  weighing-tank  arranged 
so  that  the  ends  overhang  the  scales  and  the  reservoir  below, 
the  outlet  valve,  consisting  of  a  flap  valve,  covering  an  opening 


14  ENGINE    TESTS. 

in  the  bottom  6"  or  8"  square.  With  rectangular  tanks  this 
system  can  be  employed  for  any  size  of  stationary  engine 
ordinarily  met  with. 

Where  a  meter  is  used  for  measurement  care  should  be 
observed  that  water  is  fed  through  it  at  a  uniform  rate,  and  the 
instrument  should  be  calibrated  under  conditions  in  every 
respect  like  those  of  the  test.  One  method  of  calibrating. a 
meter,  which  the  author  has  found  simple  and  fairly  satisfac- 
tory, is  to  arrange  the  piping  on  the  outlet  side  with  a  valve 
known  to  be  tight,  and  provide,  at  a  point  between  this  valve 
and  the  meter,  a  tee  with  a  branch  having  a  flexible  hose 
attached.  A  gauge  is  also  connected  to  show  the  pressure. 
The  valve  leading  to  the  hose  need  not  be  of  the  full  size  of 
the  main  line ;  for  under  the  conditions  of  the  calibration  it  dis- 
charges the  water  against  a  pressure  much  less  than  the  work- 
ing pressure,  and,  if  the  quantity  is  small,  against  practically 
no  pressure.  The  hose  is  carried  to  two  empty  barrels  located, 
preferably,  outside  of  the  building,  where  the  water  can  be  dis- 
charged without  doing  harm;  and  there  two  workmen  are 
stationed  to  manipulate  this  end  of  the  line.  In  making  the 
calibration,  the  stop  valve  in  the  main  is  closed,  and  the  branch 
valve  leading  to  the  hose  is  opened  and  so  adjusted  as  to  keep 
the  pressure  at  the  working  point.  The  pump  or  other  appara- 
tus for  feeding  is  at  the  same  time  adjusted  to  give  the  working- 
quantity  of  supply.  This  will  be  determined  by  timing  the 
readings  of  the  meter  for,  say,  one  minute.  When  the  proper 
rate  has  been  secured,  the  meter  is  read  ;  and  at  that  instant  a 
signal  is  given  to  throw  the  hose  into  one  of  the  barrels,  the 
water  during  the  preliminary  operations  having  run  to  waste. 
When  the  first  barrel  is  filled,  the  hose  is  quickly  thrown  into 
the  second  one ;  and  while  the  second  barrel  is  filling,  the  work- 
men tip  the  first  one  over  bodily  and  empty  it.  When  the 
second  barrel  is  filled,  the  hose  is  quickly  transferred  back  to 
the  first,  and  immediately  the  second  barrel  is  tipped  over  and 
emptied.  This  can  be  carried  on  as  long  as  desired,  depending 
upon  the  size  of  the  meter  and  'the  thoroughness  required.  The 
last  reading  of  the  meter  is  taken  when  the  last  barrel  becomes 


HOW   THE    TESTS    WERE    COND UC TED.  15 


filled,  accurate  count  having  been  made  of  the  whole  number. 
Subsequently  the  quantity  of  water  contained  in  the  two  bar- 
rels is  ascertained  by  weighing,  and  the  rating  of  the  meter  is 
quickly  determined  by  calculation. 

When  an  engine  is  fitted  with  a  surface  condenser,  the  meas- 
urement of  the  feed-water  can  be  somewhat  simplified  by  col- 
lecting the  water  discharged  by  the  air-pump.  In  this  case  the 
same  kind  of  apparatus  can  be  used  for  weighing ;  but  the  two 
tanks  are  reversed,  the  water  being  discharged  first  into  the 
reservoir,  and  subsequently  drawn  into  the  weighing-tank,  which 
is  placed  below  it,  and,  after  being  measured,  thrown  away. 

An  approximate  determination  of  the  feed-water  consump- 
tion can  be  made  by  water-glass  measurement,  assuming  that 
the  type  of  boiler  is  such  that  this  method  is  applicable.  The 
feed-water  is  shut  off  from  the  boilers  for  a  half  hour's  time,  or 
such  period  as  is  permissible,  and  the  rate  observed  at  which 
the  water  disappears  in  the  gauge  glasses.  Subsequently  the 
volume  consumed  in  the  observed  time  is  computed  from  the 
known  dimensions  of  the  space  occupied,  and  from  this 
the  weight  of  the  water  which  has  been  evaporated.  If  the 
water  line  is  effected  to  any  extent  by  the  condition  of  the  fires, 
it  is  necessary  in  making  these  measurements  to  observe  great 
care  that  the  conditions  of  the  fires  are  the  same  at  the  end  of 
such  a  trial  as  at  the  beginning.  In  some  boilers  the  increased 
activity  of  the  fire  causes  the  water  line  to  rise,  while  the  dead- 
ening of  the  fire  has  the  opposite  effect.  With  the  damper  wide 
open,  and  the  fire  barred  up  and  in  an  open  or  free  condition, 
there  is  great  activity  of  the  fire ;  while  with  the  damper  closed 
and  new  coal  applied,  there  is,  for  the  time  being,  a  very  marked 
reduction  in  the  intensity  of  the  heat.  The  position  of  the 
damper  and  the  thickness  and  general  characteristics  of  the  fire 
should  be  the  same  at  one  time  as  at  the  other.  It  is  best  to 
observe  this  precaution  in  all  cases,  even  when  there  is  no  sen- 
sible effect  produced  by  these  changes  in  the  fire.  It  is  also 
necessary  that  the  gauge  glass  and  the  connections  leading  from 
the  water  column  to  the  boiler  should  be  clear ;  a  condition 
which  can  be  secured  by  blowing  them  out  a  short  time  (say 


16  ENGINE    TESTS. 

one  hour)  previous  to  the  trial.  When  these  are  obstructed 
a  noticeable  effect  is  produced  upon  the  height  of  water  shown 
in  the  glass. 

It  is  also  necessary  to  be  assured  of  the  tightness  of  the  feed 
valves  and  check  valves  concerned,  that  none  of  the  water 
measured  escapes  by  leakage. 

The  author  has,  in  some  instances,  been  able  to  obtain  a 
measurement  of  the  feed-water  by  drawing  it  from  the  tank 
which  is  often  provided  in  mills  for  fire  purposes  and  other 
emergencies,  and  which  is  not  regularly  in  use.  This  tank 
being  generally  of  uniform  cross-section,  the  water  it  contains 
is  subject  to  accurate  measurement.  When  such  means  is  used 
for  measuring  feed-water,  it  is  absolutely  necessary  to  be  assured 
that  the  water  is  not  in  the  meantime  used  elsewhere  than  for 
the  test,  and  that  the  valves  connected  with  the  system  of  regu- 
lar supply  do  not  leak. 

The  orifice  method  of  measurement  is  one  which  the  author 
has  found  useful  in  a  number  of  cases.  One  instance  is  that  of 
a  1000  horse-power  compound  condensing  engine,  in  which  the 
water  from  the  hot  well  was  used  in  the  customary  manner  for 
feeding.  A  test  was  required  to  determine  the  coal  consump- 
tion of  the  plant  per  indicated  horse-power  per  hour,  under  as 
nearly  as  possible  working  practice.  The  quantity  of  feed-water 
used  was  desired ;  but  it  must  be  obtained  without  changing, 
any  more  than  necessary,  the  working  conditions.  The  hot 
well  overflow  pipe  was  too  near  the  level  of  the  suction  pipe  of 
the  pump  to  permit  of  using  the  ordinary  process  of  weighing ; 
consequently,  resort  was  had  to  orifice  measurement.  The  feed- 
tank was  supplied  from  the  overflow  of  the  hot  well  through  a 
4-in.  pipe.  The  elbow  on  this  pipe,  next  to  the  tank,  was 
replaced  by  a  4-in.  tee,,  one  branch  of  which  looked  down  and 
the  other  looked  up.  To  the  lower  branch  a  pair  of  flanges 
was  attached,  in  which  was  secured  a  horizontal  plate  having  a 
hole  If -in.  diameter ;  and  this  served  as  the  orifice.  The  plate 
was  horizontal,  and  the  discharge  from  it  was  therefore  directly 
downward  into  the  tank.  The  upper  branch  of  the  tee  con- 
tained a  stand-pipe  3  ft.  high ;  and  to  this  pipe  was  attached  a 


HOW    THE    TESTS    WERE    CONDUCTED.  17 

glass  for  showing  the  height  of  the  water  inside,  the  same  being 
graduated  in  inches  measured  from  the  face  of  the  orifice  plate. 
A  valve  in  the  4-in.  supply-pipe  served  to  regulate  the  height  of 
water  in  the  stand-pipe,  and  consequently  the  amount  passing 
through  the  orifice.  During  the  progress  of  the  test,  the  head 
of  water  in  the  stand-pipe  was  maintained  at  such  a  point  as  to 
supply  the  required  quantity  of  water;  and  a  careful  record 
was  kept  of  the  height  indicated  in  the  gauge  glass.  Subse- 
quently, when  the  pump  was  stopped,  the  orifice  was  calibrated 
by  observing  the  quantity  of  water  which  flowed  into  the  tank 
under  conditions  of  the  average  head,  the  contents  being  pre- 
viously known. 

Whatever  method  is  pursued  in  determining  the  quantity  of 
water  pumped  into  the  boilers  on  a  feed-water  test,  a  determi- 
nation should  be  made  of  the  leakage  of  the  boilers,  stop  valves, 
safety  valves,  steam-pipe  joints,  blow-off  cocks,  etc.,  concerned 
in  the  plant,  so  as  to  correct  for  such  leakage,  and  charge  the 
engine  with  only  that  quantity  of  feed-water  which  actually 
passes  into  it  as  steam  through  the  throttle  valve.  To  accom- 
plish this  object  a  leakage  trial  should  be  made  immediately 
after  the  engine  is  shut  down  at  the  close  of  the  test,  the 
pressure  being  maintained  in  the  boilers  at  a  point  nearly,  if 
not  quite,  as  high  as  the  working  pressure,  and  no  change  made 
in  the  stop  valves,  etc.,  concerned,  or  in  the  drips  or  other 
avenues  of  escape.  Observations  should  then  be  made  of  the 
height  of  water  in  the  gauge  glasses,  taking  readings  at  inter- 
vals of  ten  minutes  for  a  period  of  one  hour,  or  until  successive 
differences  in  the  ten-minute  periods  show  a  uniform  rate  of 
leakage.  By  calculating  the  weight  of  water  corresponding  to 
the  volume  lost,  as  found  by  this  test,  which  can  be  done  know- 
ing the  dimensions  of  the  boilers,  the  desired  correction  for 
leakage  is  determined.  To  make  this  test  reliable  it  is  neces- 
sary, of  course,  that  the  throttle  valve  at  the  engine  should  be 
tight.  The  tightness  of  the  throttle  valve  can  readily  be  deter- 
mined by  observing  whether  steam  blows  from  the  open  indi- 
cator-cock of  the  cylinder  when  the  steam  valve  is  wide  open, 
this  observation  being  made  at  the  end  of  the  cylinder  which  is 


18  ENGINE   TESTS. 

taking  steam.  If  it  leaks,  allowance  should  be  made  for  this 
leakage.  If  there  is  considerable  piping,  and  it  pitches  toward 
the  throttle  valve,  it  is  also  necessary  that  allowance  be  made 
for  the  steam  which  condenses  in  the  pipes  and  collects  at  the 
throttle  valve.  In  some  cases  it  will  be  seen  that  the  condi- 
tions may  be  such  that  the  determination  of  the  correction  for 
leakage  may  be  a  difficult  matter;  but  it  is  a  subject  which 
ought  always  to  receive  attention  when  the  object  of  the  test, 
as  in  the  present  instances,  is  to  determine  the  quantity  of 
steam  used  by  the  engine  alone. 

Whatever  method  of  feed- water  measurement  is  employed,  it 
is  necessary  that  the  height  of  water  in  the  gauge  glass  should 
be  the  same  at  the  end  of  the  allotted  time  of  the  test  as  at  the 
beginning.  It  is  important  also  that  the  condition  of  the  fire 
should  be  the  same  at  one  time  as  at  the  other,  because,  as 
elsewhere  noted,  the  height  of  the  water  may  be  more  or  less 
affected.  For  example,  if  the  test  begins  just  before  firing  and 
with  the  damper  closed,  or  nearly  closed,  it  should  also  end 
just  before  firing  and  with  the  damper  likewise  closed.  It  is 
better  to  overrun  the  allotted  time  or  even  to  cut  it  short,  and 
have  these  conditions  right,  than  to  overlook  them  in  the  desire 
to  make  the  duration  of  the  trial  a  predetermined  number  of 
hours  to  the  exact  minute.  If  the  height  of  the  water  at  the 
end  of  the  test  is  different  from  what  it  was  at  the  beginning, 
the  necessary  correction  estimated  from  the  corresponding  vol- 
ume of  water  is  applied  to  the  quantity  weighed.  This  correc- 
tion is  determined  with  sufficient  accuracy,  in  most  cases,  by 
calculation  from  the  known  exterior  measurements  of  the  boiler. 

INDICATING. 

It  is  unnecessary  for  the  purposes  of  this  volume  to  go  into 
a  description  of  steam-engine  indicators,  for  the  books  on  the 
subject  of  the  indicator  furnish  an  ample  amount  of  informa- 
tion of  this  character.  It  will  suffice  to  say  that  for  most  of 
the  tests  here  reported  the  instruments  used  were  either  of  the 
Tabor  or  the  Crosby  pattern,  or  both.  The  methods  of  apply- 
ing the  instruments,  however,  the  means  of  driving  them  and 


BOW    THE    TESTS    WERE    CONDUCTED.  19 

manner  of  using  them,  also  the  methods  employed  in  calibrating 
the  springs,  require  notice. 

In  nearly  all  the  indicator  work  on  the  Corliss,  and  similar 
types  of  slow-speed  engines,  the  driving-rig  has  been  some 
form  of  pantagraph,  and  in  the  large  majority  of  cases,  that 
form  known  as  the  "lazy-tongs,"  working  horizontally  and 
operated  from  the  cross-head.  The  fixed  end  of  the  lazy-tongs 
has  generally  been  applied  to  one  of  two  wooden  posts,  attached 
to  a  base-board,  which  in  turn  is  fastened  to  the  floor.  The 
second  post,  suitably  located  with  reference  to  the  first,  is  used 
for  the  support  of  a  carrier-pulley,  and  both  posts  are  securely 
fixed  in  position  by  means  of  three  wooden  braces  fastened  to 
the  floor.  This  method  of  attaching  the  lazy-tongs  has  the 
advantage  of  rigidity,  which  is  so  essential  to  a  correctly  driven 
indicator;  and  the  use  of  the  carrier-pulley  enables  the  driving- 
cord  to  be  always  led  off  in  a  line  parallel  to  the  direction  of 
motion  of  the  cross-head,  whatever  the  position  of  the  indi- 
cators with  reference  to  the  cord-pin  of  the  lazy-tongs.  The 
construction  of  a  stand  for  supporting  the  lazy-tongs  in  this 
manner  may  be  considered  crude  and  clumsy  for  permanent 
use ;  but  the  author  has  often  found  permanent  rigs  defective 
from  improper  design  or  insecurity,  due  to  gradual  wear,  and 
substituted  the  one  described.  Being  made  throughout  of 
wood,  it  is  a  device  which  can  be  quickly  put  together,  even 
where  there  is  no  carpenter-shop  at  hand  and  little  material. 
As  it  is  built  in  such  form  as  to  easily  and  positively  accom- 
plish the  desired  ends,  it  has  been  found  most  useful. 

For  a  driving-cord,  a  strong  braided  linen  fish-line  having  an 
unbraided  core  is  used,  extending  a  little  beyond  the  carrier- 
pulley  ;  and  from  this  point  to  the  indicators,  pieces  of  annealed 
brass  wire  are  used,  about  No.  25  B.W.G.  (3y  in  diameter). 
For  a  single  cylinder  two  cords  are  thus  brought  into  use  lead- 
ing from  the  same  initial  point.  In  the  case  of  tandem  cylin- 
ders, either  four  independent  cords  are  used,  or  two  independent 
cords,  each  having  branch  loops  at  appropriate  points  for  con- 
necting to  the  two  instruments.  In  some  cases  the  cords  have 
been  displaced  by  a  light  wooden  rod  driven  by  the  cord  pin  of 


20  ENGINE    TESTS. 

the  lazy-tongs,  and  moving  on  guides  attached  to  the  cylinder, 
the  direction  of  motion  being  parallel  to  it.  A  screw  fastened 
to  the  rod  at  the  proper  place  serves  to  carry  the  motion  to  the 
cord  attached  to  the  indicator.  The  use  of  the  rod  in  place  of 
the  cords  is  especially  applicable  to  tandem  engines. 

For  high-speed  engines  the  driving  apparatus  is  some  form 
of  lever  and  sector,  the  shaft  on  which  the  lever  is  mounted 
being  in  many  cases  supported  by  a  stand  bolted  to  the  frame 
of  the  engine.  In  some  engines  of  the  high-speed  compound 
class  the  driving  motion  is  derived  from  an  eccentric  fastened 
to  the  main  shaft,  the  motion  being  carried  from  this  point  to 
the  cylinder  through  a  connecting-rod  and  bell-crank  lever.  In 
these  cases  an  independent  motion  is  used  for  each  cylinder. 

It  has  been  the  custom  in  making  these  tests  to  employ  two 
indicators  for  each  cylinder,  attached  as  close  as  possible  to  the 
end  of  the  cylinder,  using  the  half-inch  connection,  a  right-angle 
elbow,  and  the  indicator-cock  furnished  with  the  instrument. 
Sometimes  a  straight-way  valve  is  placed  below  the  indicator- 
cock  for  facility  in  moving  the  same  without  shutting  down 
the  engine.  The  objections  to  long  pipes  connected  by  a  three- 
way  cock  in  the  center,  consist  in  the  increased  friction  of  the 
steam  in  passing  through  the  greater  length  of  the  pipe  with 
the  increased  number  of  bends,  and  in  the  collection  of  water 
in  the  long  horizontal  cavity  which  is  thus  brought  into  play. 
If  two  indicators  are  not  available  for  an  engine  test,  it  seems 
better  to  use  one  instrument,  and  transfer  it  from  one  end  to 
the  other,  than  to  employ  the  three-way  cock  and  have  the 
instrument  fixed  at  the  central  point  with  the  long  connections. 

On  many  of  these  tests  "  prepared  "  indicator  paper  has  been 
used,  the  instrument  being  fitted  with  metallic  marking-points. 
These  marking-points  are  made  of  brass  wire  of  suitable  size, 
which  is-  reduced  in  diameter  near  the  marking  end  to  about 
sV,  so  that  by  the  use  of  a  small  hand-vise,  such  as  watch- 
makers employ,  and  an  oil-stone,  the  marking-point  is  readily 
kept  in  shape  for  tracing  fine  lines.  The  use  of  metallic  paper 
is  much  to  be  preferred,  as  a  matter  of  convenience,  to  plain 
sheets  with  the  ordinary  lead-pencil  point,  inasmuch  as  the 


HOW    THE    TESTS    WERE    CONDUCTED.  21 

sharpening  of  the   metal   point   requires  much  the  less  atten- 
tion. 

The  driving  mechanism  for  the  work  referred  to  here  has  in 
110  case  been  any  form  of  reducing-wheel. 

GENERAL   METHOD    OF   CARRYING    ON  THE 
FEED-WATER   TEST. 

The  testing  apparatus  being  in  readiness,  and  the  engine 
working  with  the  desired  load,  the  height  of  water  in  the 
gauge  glasses  is  observed,  the  time  taken,  and  the  position  of 
the  water  in  the  reservoir  of  the  weighing  apparatus  observed. 
Thereafter  all  the  water  fed  is  weighed.  At  the  expiration  of 
the  time  determined  upon,  the  water  in  the  gauge  glasses  and 
in  the  lower  reservoir  is  brought  to  the  starting-point,  and  the 
exact  time  observed.  During  the  progress  of  the  test  indicator 
diagrams  are  taken  every  thirty  minutes,  and  sometimes  every 
twenty  minutes,  and  at  the  same  time  the  gauges  are  observed 
and  the  number  of  revolutions  per  minute  counted.  If  the 
steam  is  superheated,  the  temperature  of  the  steam  is  observed ; 
and  if  calorimeter  tests  are  made,  these  are  either  continuous 
or  made  at  convenient  intervals.  Where  special  accuracy  is 
required,  the  atmospheric  pressure  is  determined  by  observa- 
tion of  a  barometer  at  some  time  during  the  progress  of  the 
test.  For  this,  it  is  sufficient  for  all  practical  purposes  to  rely 
upon  the  record  of  the  United  States  signal  service  at  the 
nearest  station.  When  the  test  is  made  in  a  factory  running 
ten  hours  per  day,  say  five  hours  in  the  forenoon  and  five  hours 
in  the  afternoon,  the  record  in  some  instances  embraces  the 
whole  period  from  the  time  the  engine  starts  until  the  time  of 
stopping.  In  that  case  the  initial  and  final  readings  of  the 
water  glasses  are  taken  just  before  the  engine  starts,  and  just 
after  it  stops.  The  duration  is  taken  from  the  time  the  engine 
attains  its  working  speed  till  the  time  the  throttle  valve  is 
closed ;  and  no  further  account  is  taken  of  the  power  devel- 
oped while  the  engine  is  reaching  its  speed  after  first 
starting.  In  that  case,  the  first  set  of  diagrams  is  taken  not 
less  than  five  minutes  after  the  load  is  put  on ;  and  the  as- 


22  ENGINE    TESTS. 

sumption  is  made  that  the  loss  of  steam  from  condensation  and 
drips  during  the  time  the  engine  is  first  starting  and  attaining 
its  working  speed  counterbalances  the  deficiency  of  load  be- 
tween the  time  when  the  speed  is  attained  and  the  working- 
load  is  actually  applied.  In  factory  work,  the  interval  of  time 
between  the  attainment  of  the  working  speed  and  the  applica- 
tion of  the  full  load  is  usually  less  than  three  minutes. 

In  taking  diagrams  from  an  engine  with  the  object  of  deter- 
mining its  power,  it  is  not  desirable  to  limit  the  diagram  to  a 
single  revolution.  The  marking-point  of  the  indicator  should 
be  applied  long  enough  to  obtain  four  or  five  diagrams,  cor- 
responding to  that  number  of  successive  revolutions,  in  order 
that  the  effect  which  the  fluctuations  in  the  governing  mechan- 
ism has  upon  the  diagrams  may  be  provided  for.  In  working 
up  the  diagrams,  then,  the  mean  pressure  is  obtained  for  the 
average  diagram,  and  not  for  any  single  one.  By  pursuing 
this  method,  the  average  power  which  is  determined  relates  to 
several  times  as  many  diagrams  as  it  would  if  it  were  confined 
to  a  single  revolution  in  each  case.  Instances  are  frequently 
met  where  the  fluctuations  in  the  cut-off  for  half  a  dozen  suc- 
cessive diagrams  varies  from  2  to  5  per  cent  of  the  length  of 
the  stroke,  and  in  such  cases  this  matter  is  of  considerable  im- 
portance. As  a  convenience  in  working  up  the  diagrams,  a 
good  plan  to  follow  is  to  go  over  each  one  with  a  pencil,  and 
trace  with  dotted  lines  the  diagram  which  represents  an  aver- 
age of  those  made  by  the  indicator,  and  in  the  subsequent 
calculations  to  use  this  dotted  diagram.  When  a  load  is  ex- 
tremely fluctuating,  this  system  should  be  carried  further.  The 
period  of  taking  the  diagram  should  extend  over  at  least  a  full 
minute,  though  it  is  unnecessary  to  make  it  a  continuous  dia- 
gram for  this  length  of  time.  The  marking-point  can  be  pre- 
ferably applied  for  three  or  four  revolutions  at  the  beginning 
of,  say  every  ten  seconds  of  a  minute,  and  in  that  way  the 
record  applies  to  some  twenty  revolutions  spread  over  the  full 
period.  Having  these  diagrams  now  on  the  same  card,  an 
average  line  can  be  dotted  in  by  hand,  using  the  best  judgment 
after  examining  the  appearance  of  the  various  diagrams  and 
their  location. 


HOW   THE    TESTS    WERE   CONDUCTED.  23 

The  same  method  is  usefully  applied  in  tests  of  electric  rail- 
way engines.  Indeed,  except  by  some  system  of  this  kind,  no 
fair  idea  of  the  indicated  horse-power  can  be  obtained,  and  no 
good  comparison  can  be  made  between  the  indicated  horse-power 
and  the  electrical  horse-power.  In  these  engines  it  is  best  to 
make  the  interval  between  the  sets  of  diagrams  thus  obtained 
not  more  than  ten  or  fifteen  minutes.  It  should  be  arranged 
to  give  a  signal  every  ten  seconds  while  the  operation  is  going 
on,  so  that  all  the  indicators  may  be  worked  together  for  the 
three  or  four  revolutions  desired.  Likewise,  on  the  same  signal 
corresponding  readings  are  taken  of  the  electrical  instruments. 
This  is  continued  until  the  period  of  time  covered  is  two  or 
more  minutes.  The  diagrams  being  all  taken  on  the  same  card, 
without  unhooking  the  indicators,  the  means  is  at  hand  for  ob- 
taining an  average  for  the  whole  period,  as  before  pointed  out. 

LEAKAGE    TESTS    OF    VALVES    AND    PISTONS. 

The  determination  of  the  condition  of  an  engine  as  to  the 
tightness  of  the  valves  and  pistons  has  nothing  to  do  with  the 
work  of  making  a  feed-water  test,  or  of  correctly  ascertaining 
the  results.  When,  however,  it  comes  to  analyzing  the  results, 
and  ascertaining  whether  the  engine  is  working  with  a  proper 
degree  of  economy,  and  if  not,  the  reasons  for  the  waste,  it  is 
of  the  utmost  importance  that  the  matter  of  leakage  should  be 
investigated.  It  is  always  desirable,  therefore,  when  a  feed- 
water  test  is  conducted,  to  supplement  it  by  an  inspection  of  the 
valves  and  pistons  having  this  object  in  view.  This  inspection 
must  be  made  when  the  engine  is  at  rest.  The  conditions 
which  surround  the  internal  working  parts  of  an  engine  at  rest 
are  entirely  different  from  those  of  the  engine  in  motion,  and 
for  this  reason  it  is  held  by  some  that  an  examination  of  leak- 
age under  these  circumstances  gives  little  information  which 
can  be  applied  to  working  conditions.  Those  who  take  this 
view  hold  that  under  conditions  of  motion  the  quantity  of  leak- 
age is  reduced,  and  it  might  happen  that  the  leakage  in  motion 
would  be  altogether  insignificant,  although  very  serious  at  rest. 
The  author  takes  the  ground  that  the  only  course  open  in  this 


24  ENGINE    TESTS. 

matter  is  to  make  the  examination  when  the  engine  is  at  rest, 
for  certainly  no  thorough  inspection  can  be  made  when  it  is  in 
motion.  If  it  is  found  that  there  is  practically  no  leakage  at 
rest,  it  seems  reasonable  to  conclude  that  the  engine  is  tight  in 
motion.  If,  however,  there  is  leakage  at  rest,  we  can  certainly 
say  that  there  is  a  probability  of  leakage  in  motion,  although  it 
may  not  be  possible  to  judge  of  its  degree. 

The  leakage  tests  here  referred  to  are  not  quantitative ;  that 
is,  they  do  not  determine  the  exact  amount  of  leakage,  but 
rather  the  fact  as  to  whether  leakage  does  or  does  not  exist. 
They  are  intended  simply  to  give  the  observer  a  fair  idea  as  to 
the  general  condition  of  the  engine. 

Turning  to  the  methods  employed  in  testing  for  leakage,  the 
steam-valves  are  readily  disposed  of.  In  a  Corliss  engine,  it  is 
necessary  simply  to  close  the  two  admission  valves,  open  the 
two  indicator-cocks,  and  with  the  starting-bar  move  the  exhaust 
valves  first  one  way  and  then  the  other,  the  throttle  valve  be- 
ing open,  and  a  full  pressure  of  steam  being  admitted  into  the 
chest.  When  the  starting-bar  is  moved  so  as  to  close  the  ex- 
haust valve  at  the  head  of  the  cylinder,  any  leakage  of  steam 
through  the  steam  valve  at  that  end  will  be  made  to  escape  at 
the  indicator-cock,  and  thus  become  visible.  Likewise  when 
the  starting-bar  is  moved  so  as  to  close  the  exhaust  valve  at  the 
crank  end,  the  steam  which  leaks  through  the  crank-end  ad- 
mission valve  will  show  itself  at  the  open  cock.  In  making 
these  movements  of  the  starting-bar,  care  is  taken  that  the 
steam  valves  are  held  unhooked.  The  quantity  of  leakage  is 
judged  by  the  force  of  the  current  of  steam  blowing  out  of  the 
cock.  If  the  valves  are  tight  there  is  simply  a  breath  of  steam, 
or  an  entire  absence  of  vapor.  If  they  leak  badly,  the  cur- 
rent will  blow  out  of  the  indicator-cock  with  much  force  and 
noise,  and  rise  to  a  height  of  several  feet. 

In  testing  the  exhaust  valves  and  pistons  for  leakage,  the 
best  method  is  to  block  the  fly-wheel  in  such  a  position  that  the 
engine  is  taking  steam  with  the  piston  at  a  short  distance  from 
the  end  of  the  stroke,  open  the  throttle  valve,  and  observe  what 
blows  through.  It  is  well  to  try  this  if  possible  with  the 


HOW   THE    TESTS    WERE    CONDUCTED.  25 

piston  at  different  points.  If  the  end  of  the  exhaust  pipe  is 
open  to  view,  as  would  be  the  case  with  a  non-condensing 
engine,  the  steam  which  leaks  through  can  be  observed  at  the 
open  outlet.  This  can  also  be  done  in  the  case  of  a  condensing 
engine  where  there  is  a  branch  exhaust  pipe  leading  to  the  at- 
mosphere. Where  the  engine  is  condensing,  and  no  such  branch 
is  provided,  and  there  is  no  other  opening  in  the  exhaust  pipe 
in  front  of  the  condenser,  a  pretty  good  idea  can  be  obtained  of 
the  general  facts  by  observing  the  amount  which  the  condenser 
is  heated  by  the  steam  which  leaks. 

With  the  piston  in  any  given  position  in  a  Corliss  engine, 
the  leakage  on  such  tests  embraces  the  leakage  of  one  exhaust 
valve,  one  steam  valve,  and  the  piston.  To  investigate  the 
leakage  of  the  other  steam  valve  and  the  other  exhaust  valve, 
the  test  must  be  made  with  the  piston  taking  steam  on  the 
opposite  stroke.  In  either  case,  if  the  previous  inspection  of 
the  two  steam  valves  shows  them  to  be  leaking,  this  fact  must 
be  considered  in  drawing  conclusions  as  to  the  leakage  of  the 
piston  and  exhaust  valves. 

There  is  another  method  of  testing  the  leakage  of  piston  and 
exhaust  valves,  namely,  the  "  time  method."  The  fly-wheel  is 
blocked,  as  before,  with  the  piston  at  some  distance  from  the 
beginning  of  the  stroke,  the  throttle  valve  is  opened,  and  steam 
is  admitted  at  full  pressure  until  the  cylinder  is  thoroughly 
warmed.  Then  the  throttle  valve  is  shut,  and  the  length  of 
time  is  observed  which  is  required  for  the  steam  to  escape 
through  the  leaking  openings.  To  conduct  the  test  properly, 
an  indicator  is  attached  to  the  cylinder  at  the  end  containing 
the  steam,  and  a  mark  is  made  on  a  blank  card  at  intervals  of, 
say,  one-quarter  of  a  minute  from  the  time  the  throttle  valve  is 
closed  ;  and  by  this  means  the  rate  of  fall  of  pressure  and  escape 
of  steam  is  recorded.  This  test,  like  the  others,  is  qualitative, 
and  not  quantitative.  The  relative  condition  of  the  engine 
determined  from  results  of  the  time  tests  must  be  judged  by 
comparing  with  other  cases  where  known  conditions  of  excel- 
lence prevailed.  In  a  leaking  engine  the  fall  of  pressure  on  a 
test  of  this  kind  is  very  rapid.  If  the  leakage  is  serious,  the 


26  ENGINE    TESTS. 

first  observation,  after  a  quarter  minute  interval,  might  show  a 
reduction  of  pressure  covering  nearly  the  whole  range  down  to 
the  atmosphere.  On  the  contrary,  if  the  engine  is  tight,  the 
reduction  of  pressure  to  the  atmosphere  would  require  from 
five  to  ten  minutes  time.  The  author  finds  that  the  pressure 
will  not  fall  as  a  rule  more  than  fifty  per  cent  at  the  expiration 
of  one  minute  from  the  time  of  shutting  the  throttle  valve,  if 
the  engine  is  fairly  tight. 

If,  on  leakage  tests  with  the  blocked  engine,  it  is  found  that 
the  piston  and  the  two  valves  leak,  whichever  stroke  the  piston 
is  occupying,  the  piston  leakage  can  be  eliminated  by  discon- 
necting the  valve  rods  in  such  a  way  as  to  open  both  steam 
valves  and  close  both  exhaust  valves.  When  this  is  done,  the 
resulting  leakage  which  is  observed  applies  to  the  exhaust 
valves  alone. 

The  leakage  of  a  piston  can  always  be  inspected  by  removing 
the  cylinder  head  and  applying  a  pressure  behind  the  piston. 
The  leakage  then  appears  at  the  open  end  of  the  cylinder.  On 
large  engines  the  operation  of  taking  off  a  cylinder  head  is 
attended  with  considerable  labor.  The  methods  which  have 
been  described  can  be  brought  into  use  with  great  facility  and 
save  this  labor,  to  say  nothing  of  saving  time. 

The  blocking  of  the  engine  which  these  tests  require  is  a 
thing  which  should  not  be  undertaken  in  any  careless  manner. 
In  most  cases  the  masonry  foundation  of  the  engine  is  so 
arranged  that  a  piece  of  timber  can  be  placed  between  the 
spokes  of  the  wheel,  and  the  two  ends  laid  upon  or  against  the 
foundation,  the  strain  of  a  spoke  being  brought  to  bear  upon 
the  middle  of  the  timber.  This  timber  should  be  of  ample  size, 
say,  a  12  in.  or  14  in.  stick  of  hard  pine  for  an  engine  of  1000 
horse-power,  the  points  of  support  at  the  two  ends  being  not 
over  8  ft.  apart.  The  position  of  the  arm  should  be  brought  as 
nearly  as  possible  to  the  proper  point  before  the  block  is  intro- 
duced, the  leeway  being  filled  in  not  by  subsequently  moving 
the  engine,  but  by  the  introduction  of  wooden  filling-pieces  and 
wedges.  In  the  case  of  an  engine  having  a  shaft  with  two 
cranks  and  a  solid  bed  beneath  each  one,  the  engine  can  be 


HOW   THE    TESTS    WERE    CONDUCTED.  27 

readily  blocked  in  certain  positions  by  standing  a  piece  of  tim- 
ber endwise,  reaching  from  the  end  of  the  crank  to  the  floor 
or  bed,  or  by  putting  in  a  nnmber  of  wooden  blocks  laid  flat, 
and  building  up  to  the  desired  height.  Here,  again,  the  crank- 
pin  should  be  brought  to  the  required  position  before  the  blocks 
are  put  in,  and  filling-pieces  should  be  applied  to  make  up  the 
leeway,  rather  than  move  the  engine  and  run  the  risk  of  injury 
by  bringing  up  solid  against  the  blocks. 

Leakage  tests  of  the  valve  in  the  case  of  single-valve  engines 
cannot  be  made  as  satisfactorily  as  those  in  four-valve  engines, 
for  if  the  valve  leaks  excessively  it  is  difficult  to  locate  by  these 
methods  the  exact  place  of  the  leak.  The  best  that  can  be 
done  is  to  place  the  valve  on  its  center  covering  both  ports, 
and  try  it  under  a  full  steam  pressure.  The  same  course  can 
be  followed  in  testing  the  piston  as  that  described  for  the  four- 
valve  engines.  In  a  leaking  engine  of  this  type,  it  is  usually 
necessary  to  test  the  piston  with  the  cylinder  head  removed 
before  the  investigation  is  complete. 

It  is  needless  to  call  attention,  in  more  than  a  passing  way, 
to  the  test  of  piston  leakage  in  an  engine  which  is  single-acting. 
In  a  Westinghouse  engine,  for  example,  the  leakage  of  the 
piston  is  revealed  by  simply  swinging  off  the  cover  of  the  crank 
case,  and  observing  at  once  what  escapes  from  the  periphery 
of  the  piston,  the  engine  being  blocked  and  stearii  pressure 
admitted  into  the  cylinder. 

The  foregoing  remarks  on  the  subject  of  leakage  apply  to 
simple  engines.  In  the  case  of  compound  engines  the  work  is 
to  some  extent  simplified.  For  example,  in  testing  the  leakage 
of  the  high-pressure  exhaust  valves  and  piston,  the  escape  of 
steam  is  observed  by  opening  the  indicator-cock  on  the  end  of 
the  low-pressure  cylinder  which  is  taking  steam,  and  observ- 
ing what  blows  through.  Again,  in  testing  the  low-pressure 
exhaust  valves  and  piston  by  the  time  method,  steam  is  ad- 
mitted into  the  receiver  until  the  desired  pressure  is  reached, 
then,  after  the  cylinder  has  been  thoroughly  warmed,  and  the 
supply  shut  oft,  the  drop  in  pressure  is  observed  by  reading  the 
receiver  gauge  and  keeping  a  record  of  this.  A  similar  course 
is  followed  in  testing  the  leakage  of  triple-expansion  engines. 


28  ENGINE    TESTS. 


CALIBRATION    OF    INSTRUMENTS. 

For  a  satisfactory  comparison  of  the  steam-pipe  gauge  with 
the  initial  pressure  shown  by  the  diagram,  the  best  plan  is  to 
compare  the  gauge  and  the  indicator  without  changing  them 
from  their  working  positions.  This  can  be  done  at  the  same 
time  that  the  leakage  tests  are  in  progress,  as,  for  example, 
when  testing  the  piston  and  exhaust  valves,  the  fly-wheel  being 
blocked,  and  the  throttle  valve  and  admission  valve  set  wide 
open.  By  taking  the  reading  of  the  steam  gauge  and  that  of 
the  indicator  at  the  same  time  (the  latter  being  done  by  open- 
ing the  indicator-cock,  then  drawing  a  short  line  on  the  blank 
card  which  has  been  applied  for  the  purpose),  not  only  will  the 
error  of  the  gauge  itself  be  allowed  for,  but  also  the  error  pro- 
duced by  the  head  of  water  contained  in  the  gauge  pipe,  if  any 
such  error  exists.  This  comparison  alone  is  sufficient  to  estab- 
lish the  difference  in  pressure  between  that  in  the  main  pipe 
(or  in  the  boiler  to  which  the  gauge  is  attached)  and  the 
initial  pressure  in  the  cylinder  of  the  working-engine,  whether 
the  gauge,  or  indicator,  or  both,  are  in  themselves  correct  or  in 
error.  The  gauge  is  then  calibrated  by  reference  to  a  standard, 
and  the  accuracy  of  the  indicator  is  established  at  the  particular 
pressure  used.  This  single  calibration  is  considered  in  many 
cases  sufficient  for  determining  the  correct  scale  of  the  indicator 
in  question.  ( 

The  most  satisfactory  method  of  determining  the  correctness 
of  the  gauge,  is  to  remove  it  from  its  place,  and  attach  it  to  a 
dead  weight  testing-apparatus,  of  the  form  sold  by  the  steam- 
gauge  manufacturers,  in  which  the  pressure  is  produced  by 
sealed  weights  resting  upon  the  top  of  a  vertical  plunger  of 
known  area,  the  pressure  being  transmitted  to  the  gauge 
through  the  medium  of  oil  or  glycerine.  The  convenience  of 
this  method  and  the  portability  of  the  apparatus,  together  with 
its  extreme  reliability,  place  it  ahead  of  all  other  systems  for 
calibrating  gauges.  Having  made  the  calibration,  the  indica- 
tion of  the  gauge  in  its  working  position  must  be  corrected  for 
the  head  of  water  in  the  supply-pipe  of  the  gauge,  if  any  exists, 
whether  it  be  to  increase  the  indication  or  to  reduce  it. 


HOW   THE    TESTS    WERE   CONDUCTED.  29 

The  calibration  of  the  indicator  springs  used  on  the  tests 
reported  in  this  volume  has  in  many  cases  been  carried  on  by 
testing  them  under  the  action  of  dead  weights,  and  correcting 
the  result  thus  found  by  a  percentage  of  allowance  for  the 
reduced  tension  caused  by  the  heat  of  the  steam  in  which  they 
ordinarily  work.  The  author's  testing-apparatus  consists  of  a 
scale-beam  mounted  on  knife  edges,  on  one  end  of  which  the 
weights  are  suspended.  The  movement  of  the  beam  at  the 
other  end  is  transmitted  upward  by  means  of  a  vertical  adjust- 
able  rod  extending  to  the  under  side  of  the  indicator  piston. 
The  tests  are  made  with  the  highest  pressure  to  which  the 
springs  are  subjected,  and  from  this  point  down  to  the  atmos- 
phere at  uniform  reductions.  The  apparatus  is  operated  so  as 
to  get  an  average  reading,  whether  the  pressure  is  going  up  or 
going  down.  This  is  done  each  time  by  pushing  the  scale-beam 
down  as  far  as  it  will  go,  and  drawing  a  line  on  the  indicator- 
card,  then,  without  changing  the  weight,  pushing  the  same 
upward  as  far  as  it  will  go,  and  marking  another  line.  When 
the  lines  are  measured,  the  mean  of  the  two  is  selected  as  the 
true  indication.  The  springs  are  in  some  cases  compared  under 
different  pressures  with  a  correct  steam  gauge,  admitting  the 
steam  directly  into  the  indicator,  and  subjecting  it  as  near  as 
possible  to  its  working  conditions  of  temperature.  In  making 
calibrations  under  steam,  difficulties  are  often  experienced  in 
obtaining  satisfactory  indications,  owing  to  the  friction  of  the 
piston  of  the  indicator  under  the  action  of  the  continuously 
applied  pressure.  This  is  overcome,  provided  the  pressure  is 
maintained  at  a  constant  point,  by  drawing  two  lines  with  the 
instrument,  one  when  the  pencil-arm  is  pushed  down  with  the 
finger  as  far  as  it  will  go,  and  the  second  when  the  arm  is 
pushed  up  as  far  as  it  will  go,  the  true  indication  then  being 
taken  as  the  mean  of  the  two.  When  a  set  of  indicator  springs 
has  once  been  calibrated,  and  their  exact  scales  obtained,  the 
dead-weight  apparatus  above  referred  to  furnishes  a  much  more 
satisfactory  means  for  future  determinations,  and  for  showing 
the  changes  in  the  scale  which  may  take  place  under  continued 
use,  than  the  steam-testing  apparatus,  for  the  reason  of  its 


30  ENGINE    TESTS. 

greater  simplicity  and  ease  of  operation,  together  with  its  free- 
dom from  the  particular  errors  noted. 

In  calibrating  the  springs  for  pressures  below  the  atmosphere, 
the  dead-weight  apparatus  referred  to  is  not  applicable,  and 
resort  has  been  had  in  these  tests  to  comparison  with  a  mercury 
gauge,  or  with  a  standard  vacuum  gauge,  the  former  being  pre- 
ferred. In  making  these  comparisons  in  the  shop  or  laboratory 
it  is  necessary  to  obtain  a  vacuum  by  the  use  of  some  form  of 
pump  or  exhauster,  and  this  often  proves  an  inconvenience. 
For  this  reason  the  author  has  been  in  the  habit  of  making 
them  in  the  engine  room  where  the  indicators  are  being  used, 
and  where  a  vacuum  is  obtained  by  connecting  the  testing- 
apparatus  with  the  condenser.  All  that  is  required  for  ap- 
paratus is  the  connection  to  the  condenser,  a  tee  for  the 
attachment  of  the  indicator-cock,  and  a  mercury  gauge  applied 
to  one  end  of  the  tee.  With  this  apparatus  the  spring  can  be 
calibrated  down  to  the  lowest  pressure  to  which  it  is  subjected. 
It  is  desirable  to  make  the  calibration  of  an  indicator  spring 
that  is  used  for  pressures  below  the  atmosphere  under  condi- 
tions of  vacuum  as  well  as  under  conditions  of  pressure;  for  the 
fact  that  the  spring  is  correct  when  subjected  to  compression,  as 
it  is  when  a  pressure  is  applied  to  it,  furnishes  no  positive 
assurance  that  it  is  correct  under  tension,  as  it  is  when  it  is 
subjected  to  a  vacuum. 

It  is  of  no  little  importance  that  the  scale  of  the  spring 
should  be  known  within  reasonable  limits  of  error;  for  upon 
this  knowledge  depends  the  whole  accuracy  of  the  indicator 
work,  and  consequently  of  all  the  results  of  the  tests  depending 
upon  it. 

MANNER    OF    WORKING    UP    THE    TESTS. 

The  results  of  the  feed-water  tests  are  computed  from  the 
hourly  consumption  of  feed-water  corrected  for  the  leakage  of 
the  boilers,  pipes,  and  connections,  as  explained,  and  the  indi- 
cated horse-power  developed.  The  "  steam  accounted  for  by 
the  indicator "  is  determined  from  measurements  of  the  dia- 
grams and  computations  based  thereon. 


HOW    THE    TESTS    WERE    CONDUCTED.  31 

The  indicator  cards  relating  to  the  tests  reported  here  have, 
as  a  rule,  been  measured  by  a  polar  planimeter.  The  average 
obtained  by  going  over  the  line  of  the  diagram  at  least  twice  is 
the  reading  taken. 

The  mean  effective  pressure  is  determined  by  dividing  the 
scale  of  the  spring  by  the  length  of  the  diagram  expressed 
in  inches  and  decimals  of  an  inch,  and  multiplying  the  quo- 
tient by  the  area  in  square  inches.  The  length  of  the  dia- 
grams, which  is  nearly  constant,  is  found  by  selecting,  say  three 
sets  out  of  every  ten  taken  on  the  test,  and  obtaining  the 
average  length  from  those  three.  The  horse-power  is  computed 
by  multiplying  the  "horse-power  constant"  for  the  cylinder 
under  consideration  by  the  speed  in  revolutions  per  minute,  and 
by  the  mean  effective  pressure.  The  horse-power  constant  is 
the  power  developed  in  the  cylinder,  assuming  one  pound  mean 
effective  pressure  and  a  speed  of  one  revolution  per  minute. 
It  is  obtained  by  multiplying  the  mean  of  the  areas  of  the  two 
sides  of  the  piston  in  square  inches  by  twice  the  length  of  the 
stroke  in  feet,  and  dividing  the  product  by  33,000.  The  mean 
effective  pressure  used  is  the  mean  of  the  two  measurements 
obtained  at  the  two  ends  of  the  cylinder.  In  the  detail  tables, 
giving  the  data  and  the  results  of  the  tests  here  reported,  the 
horse-power  constant  for  each  cylinder  is  given ;  and  the  figures 
of  indicated  horse-power  in  any  case  are  the  result  of  multipli- 
cation of  this  constant,  the  revolutions  given  per  minute,  and 
the  mean  effective  pressure.  For  example,  in  the  case  of 
Engine  No.  1,  which  has  a  single  cylinder  23"  diameter,  5' 
stroke,  with  one  piston-rod  3^'7  in  diameter,  the  horse-power 
constant  is  .1247,  the  speed  74.7  r.p.m.,  and  the  m.e.p.  33.08 
Ibs.  The  indicated  horse-power,  viz.,  305.2,  is  the  product  of 
these  three  quantities. 

The  water  per  indicated  horse-power  per  hour  is  found  by 
simply  dividing  the  hourly  consumption  of  water  by  the  indi- 
cated horse-power.  In  the  example  referred  to,  the  hourly  con- 
sumption being  8477  Ibs.,  the  feed-water  per  I.H.P.  per  hour  is 
8477  divided  by  305.2  equals  27.77  Ibs. 

The  method  of  determining  the  quantity  of  steam  "  accounted 


32  ENGINE    TESTS. 

for  by  the  indicator"  consists  -in  measuring  the  diagrams  for 
the  necessary  data,  and  using  the  formula 

i^°  [(c  +  e)  Wx  -  (h  +  e)  Wh] 
m.e.p.  L 

in  which  "  m.e.p."  is  the  mean  effective  pressure  measured  from 
the  diagrams  as  pointed  out ;  "  c  "  the  proportion  of  the  forward 
stroke  completed  either  at  cut-off  or  release,  according  as  the 
determination  is  made  at  one  point  or  another ;  "  h  "  the  pro- 
portion of  the  return  stroke  uncompleted  at  compression ;  "  e  " 
the  proportion  of  the  clearance  space  ;  "  Wx  "  the  weight  of  one 
cubic  foot  of  steam  at  the  cut-off  or  release  pressure ;  and 
"  Wh  "  the  weight  of  one  cubic  foot  of  steam  at  the  compres- 
sion pressure. 

The  points  on  the  diagram  where  these  measurements  are 
taken  are  illustrated  in  the  sample  diagram  Fig.  1  given  below. 
These  points  are  located  as  follows :  The  point  of  cut-off  is 
marked  at  the  beginning  of  the  expansion  line  after  the  steam 
valve  has  completely  closed.  It  is  at  the  point  where  the  curve 
changes  its  direction  from  that  due  to  the  gradually  closing 
steam  valve  to  that  of  the  expansion  line.  The  point  of  re- 
lease is  marked  at  the  end  of  the  expansion  line  just  before 
the  curve  begins  to  drop,  due  to  the  opening  of  the  exhaust 
valve.  Likewise  the  compression  point  is  fixed  at  the  begin- 
ning of  the  true  compression  line,  or  at  the  end  of  the  curve 
formed  by  the  gradually  closing  exhaust  valve.  The  principle 
followed  is  to  locate  the  points  of  cut-off  and  release  so  as  to 
account  for  all  the  steam  present  in  the  cylinder  at  the  instant 
the  steam  valve  is  closed,  and  for  all  the  expanded  steam 
present  just  before  the  exhaust  valve  opens.  The  compression 
point  is  located  with  the  idea  of  obtaining  a  measurement  of 
all  the  exhaust  steam  which  is  retained  in  the  cylinder  at  the 
moment  the  exhaust  valve  is  closed. 

In  all  these  tests  the  computations  are  made  both  at  the  cut- 
off point  and  the  release  point.  It  is  desirable  to  do  this,  be- 
cause there  is  often  a  considerable  difference  between  the  two 
quantities ;  and  where  there  is  such  a  difference,  much  more  can 


HOW    THE    TESTS    WERE    CONDUCTED.  33 


be  learned  from  the  examination  of  the  steam  accounted  for  at 
cut-off  than  that  accounted  for  at  release.  The  difference  in 
the  work  done  during  expansion  is  not  proportional  to  the  dif- 
ference in  the  steam  accounted  for;  and,  consequently,  the 
actual  loss  of  economy  due  to  cylinder  condensation  and  leak- 
age is  more  closely  measured  by  the  percentage  which  is 
accounted  for  at  cut-off  than  by  the  percentage  accounted  for 
at  release.  Between  the  two,  if  only  one  computation  is  to  be 
made,  it  is  better  to  use  the  cut-off  point  than  the  release  point. 


Fig.    1. 

The  proportions  uc"  and  "h"  are  found  by  measuring  the  en- 
tire length  of  the  diagram,  first  erecting  perpendiculars  at  the 
extreme  points,  and  then  measuring  the  length  up  to  the  point 
marked,  dividing  one  by  the  other,  and  ascertaining  the  result- 
ing proportion  expressed  in  a  decimal.  The  proportion  "  e  "  for 
the  clearance  may  be  found  either  by  measurement  of  the 
clearance  spaces  from  drawings  of  the  cylinder  and  valves  or 
from  actual  test.  The  latter  is  to  be  preferred ;  for  drawings, 
however  correct  in  themselves,  do  not  show  the  exact  measure- 
ments of  the  material,  especially  of  the  ports  and  passages 
which  are  in  the  state  of  rough  casting. 

To  measure  the  clearance  by  actual  test,  the  engine  is  carefully 
set  on  the  centre,  with  the  piston  at  the  end  where  the  measure- 
ment is  to  be  taken.  Assuming,  for  example,  a  Corliss  engine, 
the  best  method  to  pursue  is  to  remove  the  steam-valve  so  as 
to  have  access  to  the  whole  steam-port,  and  then  fill  up  the 


34  ENGINE    TESTS. 

clearance  space  with  water  which  is  poured  into  the  open  port 
through  a  funnel.  The  water  is  drawn  from  a  receptacle  contain- 
ing a  sufficient  quantity,  and  this  has  previously  been  measured. 
When  the  whole  space,  including  the  port,  is  completely  filled, 
the  quantity  left  is  measured,  and  the  difference  shows  the 
amount  that  has  been  poured  in.  The  measurement  can  be 
most  easily  made  by  weighing  the  water,  arid  the  corresponding 
volume  determined  by  calculation.  The  proportion  required  in 
the  formula  is  the  volume  in  cubic  inches  thus  found,  divided 
by  the  volume  of  the  piston  displacement,  also  in  cubic  inches, 
and  the  result  expressed  as  a  decimal. 

The  only  difficulty  which  arises  in  measuring  the  clearance 
in  this  way  is  that  occurring  when  the  exhaust  valve  and 
piston  are  not  tight,  so  that,  as  the  water  is  poured  in,  it  flows 
away  and  is  lost.  If  the  leakage  is  serious,  no  satisfactory 
measurement  can  be  made,  and  it  is  better  to  depend  upon  the 
volume  calculated  from  the  drawing.  If  not  too  serious,  how- 
ever, an  allowance  can  be  made  by  carefully  observing  the 
length  of  time  consumed  in  pouring  in  the  water;  then,  after 
a  portion  of  the  water  has  leaked  out,  fill  up  the  space  again, 
taking  the  time  and  measuring  the  quantity  thus  added,  deter- 
mining in  this  way  the  rate  at  which  the  leakage  occurs.  Data 
will  thus  be  obtained  for  the  desired  correction. 

In  the  tests  here  reported  the  clearance  has  not,  as  a  rule, 
been  determined  by  actual  measurement  in  the  manner  noted, 
nor  even  in  all  cases  by  the  calculation  from  the  drawing.  In 
cases  where  the  proportion  of  clearance  is  assumed,  the  assump- 
tion is  based  on  the  known  clearance  of  similar  classes  of  engines, 
determined  either  by  water  measurement  or  calculation.  The 
effect  which  a  small  error  in  the  clearance  may  have  upon  the 
result  of  the  computation  of  steam  accounted  for  is  not  of  a 
serious  nature,  unless  it  is  a  case  where  the  cut-off  is  very  short. 
For  example,  if  the  steam  accounted  for  with  a  clearance  of  five 
per  cent  comes  out  TW  of  the  feed-water  consumption,  the  re- 
sult with  a  clearance  of  4  %  would  be  T7o3<j,  changing  the  pro- 
portion about  T§Q  at  cut-off  and  much  less  at  release. 

In  compound  and  other  multiple  expansion  engines  the  same 


HOW   THE    TESTS    WERE    CONDUCTED.  35 

formula  for  determining  the  steam  accounted  for  by  the  indica- 
tor is  used  as  that  given  above,  but  it  must  be  adapted  to  the 
type  of  engine.  The  only  change  required  in  the  formula  is 
in  the  mean  effective  pressure.  Here  the  quantity  used  when 
determining  the  steam  accounted  for  in  any  given  cylinder  is 
the  collective  mean  effective  pressure  cf  all  the  cylinders 
assumed  to  be  referred  to  the  one  under  consideration.  In  the 
case  of  the  high-pressure  cylinder  of  a  compound  engine  the 
quantity  to  be  used  is  the  sum  of  the  mean  effective  of  the  H.  P. 
cylinder  and  a  quantity  representing  the  m.e.p.  of  the  low-pres- 
sure cylinder  referred  to  the  high-pressure  cylinder;  that  is,  the 
mean  effective  pressure  in  the  low-pressure  cylinder  multiplied 
by  the  ratio  of  the  volume  of  the  L.  P.  cylinder  to  the  H.  P. 
cylinder.  If  the  ratio  is  4  to  1,  the  m.e.p.  of  the  low-pressure 
cylinder  is  to  be  multiplied  by  four  to  determine  the  quantity 
desired.  Likewise  the  quantity  to  be  used  for  computing  the 
steam  accounted  for  in  the  low-pressure  cylinder  is  the  sum  of 
the  mean  effective  pressure  in  that  cylinder,  and  the  mean  effec- 
tive pressure  in  the  H.  P.  cylinder  divided  by  the  ratio  of  the 
volume  of  the  L.  P.  cylinder  to  the  H.  P.  cylinder.  In  the 
instance  given  it  would  be  the  mean  effective  in  the  H.  P. 
cylinder  divided  by  4.  In  a  triple  expansion  engine  the  mean 
effective  pressure  to  be  used  for  computing  the  steam  accounted 
for  in  the  L.  P.  cylinder  is  the  sum  of  the  mean  effective  pres- 
sure of  that  cylinder ;  that  of  the  m.  e.  p.  of  the  H.  P.  cylinder 
divided  by  the  ratio  of  volume  of  the  L.  P.  cylinder  to  that  of 
the  H.  P.  cylinder,  and  the  m.e.p.  of  the  intermediate  cylinder 
divided  by  the  ratio  of  the  volume  of  the  L.  P.  cylinder  to  that 
of  the  intermediate  cylinder.  Likewise  the  quantity  to  be  used 
for  the  intermediate  cylinder  is  the  sum  of  three  quantities, 
namely,  the  m.e.p.  of  the  intermediate  cylinder,  the  m.e.p.  of 
the  H.  P.  cylinder  divided  by  the  ratio  of  the  volume  of  the 
intermediate  cylinder  to  that  of  the  H.  P.  cylinder,  and  the 
m.e.p.  of  the  L.  P.  cylinder  multiplied  by  the  ratio  of  the  volume 
of  the  L.  P.  cylinder  to  that  of  the  intermediate  cylinder. 

As  an  example  of  the  proper  method  of  computing  the  equiv- 
alent mean  effective  pressure  referred  to  either  cylinder  of  a 


36  ENGINE    TESTS. 

compound  engine,  we  may  take  the  case  of  Engine  No.  32,  in 
which  the  ratio  of  volumes  of  the  cylinders  is  as  1  to  3.43,  and 
the  mean  effective  pressure  in  the  two  cylinders  41.26  Ibs.  and 
9.28  Ibs.  respectively.  The  equivalent  m.e.p.  to  be  used  in 
computing  the  steam  accounted  for  in  the  H.  P.  cylinder  is 
46.26  +  (9.28  x  3.43)  =  41.26  +  31.83  =  73.09.  For  the  low- 

A  ~f    O£? 

pressure  cylinder  the  quantity  is  9.28  X  '  =  9.28  +  12.03 
=  21.31. 

As  an  example  of  this  method  applied  to  a  triple  expansion 
engine  we  may  take  the  case  of  Engine  No.  59,  in  which  the 
ratios  of  volumes  are  as  1  to  2.94  to  6.5,  and  the  mean  effec- 
tive pressures,  60.56  Ibs.,  13.22  Ibs.,  and  10.16  Ibs.  respectively. 
The  quantity  to  be  used  for  the  H.  P.  cylinder  is  60.56  + 
(13.22  x  2.94)  +  (10.16  x  6.05)  =  60.56  +  38.87  +  66.04  = 
165.47.  The  quantity  for  the  intermediate  cylinder  is  13.22  Ibs. 

+  T5T  +  (10'16  x  ^5i>  =  20'6  +  13'22  +  22'46  =  56'28' 

For  the  low-pressure  cylinder  the  quantity  is  10.16  +  (13.22  x 

^±  )   +  ^  =  9.82  +5.98+  10.16  =  25.46. 
b.o  o.o 

The  weights  of  steam  per  cubic  foot  used  in  the  formulae  for 
determining  the  steam  accounted  for  in  the  tests  under  con- 
sideration are  those  deduced  from  Regnault's  experiments  as 
given  in  D.  K.  Clark's  Manual. 

The  following  examples  will  serve  to  illustrate  the  use  of 
the  formulae,  one  case  being  a  single  expansion  engine  and  the 
other  a  triple  expansion. 


Engine  No.  22,  Simple  Condensing  Engine. 

Clearance ,....;    •*..'-:     ..  ;     ,    ..-   .     .'    ,......«  2% 

Cut-off  pressure  above  zero  .     .   •„    ~.     .' .  75.6        Ibs. 

Weight  per  cubic  foot  at  cut-off  pressure    \     /   .     .     .     ...  .1773 

Release  pressure     .     .     .    ^  "  .' ...     .  15.5 

Weight  per  cubic  foot  at  release  pressure .  .0399 

Mean  effective  pressure    ". 37.17 

Compression  pressure 3 

Weight  per  cubic  foot  at  compression  pressure .0085 


HOW   THE    TESTS    WERE    CONDUCTED.  37 

Proportion  of  direct  stroke  completed  at  cut-off    ......  .172 

Ditto  at  release  ...............     .     .  .903 

Proportion  of  return  stroke  uncompleted  at  compression    .     .     .  .048 


The  steam  accounted  for  at  cut-off  is      »t       [(.172  +  .02) 

37.17 

x  .1773  -  (.048  +.02)  x  .0085]  =  369.9  x  (.03404  -  .00056) 
=  369.9  x  .03348  =  12.39.     The  steam  accounted  for  at  release 

is     18'750     f  (.903  +  .02)  x  .0399  -  (.048  +  .02)  x  .0085  = 
37.17 

369.9  (.03682  -  .00056)  =  369.9  x  .03626  =  13.41. 


Engine  No.  59— Triple  Expansion. 

H.  P.   Cylinder  at  Cut-off. 

Clearance 2.5  % 

Cut-off  pressure 145.2        Ibs. 

Weight  per  cubic  foot  at  cut-off  pressure .3277    " 

Compression  pressure 46.8         " 

Weight  per  cubic  foot  at  compression  pressure .1129    " 

Mean  effective  pressure 60.56       " 

M.  E.  P.  of  all  the  cylinders,  referred  to  H.  P.  cylinder     .     .     .  165.47       " 

Proportion  of  direct  stroke  completed  at  cut-off .346 

Proportion  of  return  stroke  uncompleted  at  compression   .     .     .  .006 


The  steam  accounted  for  at  cut-off  is   I"  *          [  (.346  +  .025) 

loo. 47 

x  .3277  -  (.006  +  .025)  x  .1129]  =  83.1  x  (.1216  -  .0035) 
=  83.1  x  .1181  =  9.81. 


Intermediate  Cylinder  at  Cut-off. 

Clearance 2.5  % 

Cut-off  pressure 38.7       Ibs. 

Weight  per  cubic  foot  at  cut-off  pressure     ........  .0945    " 

Mean  effective  pressure 13.22       " 

M.  E.  P.  of  all  the  cylinders,  referred  to  the  intermediate  cylinder,  56.28       " 

Compression  pressure 20.7         " 

Weight  per  cubic  foot  at  compression  pressure .0524    u 

Proportion  of  stroke  completed  at  cut-off .406 

Proportion  of  return  stroke  uncompleted  at  compression  .     .     .  .008 


38  ENGINE    TESTS. 

The  steam  accounted  for  at  cut-off  is,  -=-^- —  X  [  (.406  + 

5b.28 

.025)  x  .0945  -  (.008  +  .025)  x  .0524]  =  244.3  x  (.0407  - 
.0017)  =  244.3  x  .039  -  9.53. 

L.  P.   Cylinder  at  Cut-off. 

Clearance 2.5  % 

Cut-off  pressure 16.0        Ibs. 

Weight  per  cubic  foot  at  cut-off  pressure .  .0411  " 

Mean  effective  pressure 10.16  "  " 

M.  E.  P.  of  all  the  cylinders,  referred  to  L.  P.  cylinder     .     .     .  25.46  " 

Compression  pressure 2.3  " 

Weight  per  cubic  foot  at  compression  pressure .0066  " 

Proportion  of  stroke  completed  at  cut-off .357 

Proportion  of  return  stroke  uncompleted  at  compression    ...  0 

The  steam  accounted  for  at  cut-off  is,  — ' — -  [  (.357  +  .025) 

x  .0411  --  (.025  x  .0066)  ]  =  540.1  x  (.0157  --  .00017)  = 
540.1  x  .01553  =  8.39. 

It  is  unnecessary  to  give  the  computations  for  the  release 
points  of  these  diagrams,  the  method  being  illustrated  in  the 
example  given  above  for  Engine  No.  22. 

13  750 

The   following   table   gives   the   quantity   -  for    mean 

effective  pressures  running  from  10  to  100,  advancing  by  two- 
tenths  of  a  pound;  and  from  100  to  200  advancing  by  pounds. 


HOW   THE    TESTS    WERE   CONDUCTED. 

13750 


39 


Table  of 


M.  E.  P. 


M.  E.P. 

13750 

M.  E.P. 

13750 

M.  E.  P. 

13750 

M.E  .  P. 

13750 

M.E.  P. 

M.  E.  P. 

M.E.  P. 

M.E.  P. 

10.0 

1375.0 

20.0 

687.5 

30.0 

458.3 

40.0 

343.8 

.2 

1348. 

.2 

680.7 

.2 

455.3 

_2 

342.0 

.4 

1322.1 

.4 

674.0 

.4 

452.3 

.4 

340.3 

.6 

1297.1 

.6 

667.5 

.6 

449.3. 

.6 

338.7 

.8 

1273.1 

.8 

661.1 

.8 

446.4 

.8 

337. 

11.0 

1250. 

21.0 

654.8 

31.0 

443.5 

41.0 

335.3 

.2 

1227.7 

.2 

648.6 

.2 

440.7 

.2 

333.7 

.4 

1206.1 

.4 

642.5 

.4 

437.9 

.4 

332.1 

.6 

1185.4 

.6 

636.6 

.6 

435.1 

.6 

330.5 

.8 

1165.3 

.8 

630.7 

.8 

432.4 

.8 

328.9 

12.0 

1145.8 

22.0 

625.0 

32.0 

429.7 

42.0 

327.4 

.2 

1127.1 

.2 

619.4 

.2 

427. 

.2 

325.8 

.4 

1108.9 

.4 

613.8 

.4 

424.4 

.4 

324.3 

.6 

1091.3 

.6 

608.4 

.6 

421.8 

.6 

322.8 

.8 

1074,2 

.8 

603.1 

8 

419.2 

.8 

321.3 

13.0 

1057.7 

23.0 

597.8 

33.0 

416.7 

43.0 

319.8 

.2 

1041.7 

2 

592.7 

.2 

414.1 

.2 

318.3 

.4 

1026.1 

A 

587.6 

.4 

411.7 

.4 

315.8 

.6 

1011. 

.6 

582.6 

.6 

4092 

.6 

315.4 

.8 

996.4 

.8 

577.7 

.8 

406.8 

.8 

313.9 

14.0 

982.1 

24.0 

572.9 

34.0 

404.4 

44.0 

312.5 

.2 

968.3 

.2 

568.2 

.2 

402. 

.2 

311.1 

.4 

954.9 

.4 

563.5 

.4 

399.7 

.4 

309.7 

.6 

941.8 

.6 

558.9 

.6 

397.4 

.6 

308.3 

.8 

929.0 

.8 

554.4 

.8 

395.1 

.8 

306.9 

15.0 

916.7 

25.0 

550. 

35.0 

392.8 

45.0 

305.6 

.2 

904.6 

.2 

545.6 

.2 

390.6 

.2 

304.2 

.4 

892.9 

.4 

541.3 

.4 

388.4 

.4 

302.9 

.6 

881.4 

.6 

537.1 

.6 

386.2 

.6 

301.5 

.8 

870.2 

.8 

532.9 

.8 

384.1 

.8 

300.2 

16.0 

859.4 

26.0 

528.8 

36.0 

381.9 

46.0 

298.9 

.2 

848.8 

.2 

524.8 

.2 

379.8 

.2 

297.6 

.4 

838.4 

.4 

520.8 

.4 

377.7 

.4 

296.3 

.6 

828.3 

.6 

516.9 

.6 

375.7 

.6 

295.0 

.8 

818.4 

.8 

513. 

.8 

373.6 

.8 

293.8 

17.0 

808.8 

27.0 

509.2 

37.0 

371.6 

47.0 

292.5 

.2 

799.4 

.2 

505.5 

.2 

369.6 

.2 

291.3 

.4 

790.2 

.4 

501.8 

.4 

367.6 

.4 

290.0 

.6 

781.2 

.6 

498.2 

.6 

365.7 

.6 

288.8 

.8 

772.5 

.8 

494.6 

.8 

363.7 

.8 

287.6 

18.0 

763.9 

28.0 

491.1 

38.0 

361.8 

48.0 

286.4 

.2 

755.5 

.2 

487.6 

.2 

359.9 

.2 

285.2 

.4 

747.3 

.4 

484.2 

.4 

358.1 

.4 

284.1 

.6 

739.2 

.6 

480.8 

.6 

356.2 

.6 

282.9 

.8 

731.4 

.8 

477.4 

.8 

354.4 

.8 

281.7 

19.0 

723.7 

29.0 

474.1 

39.0 

352.6 

49.0 

280.6 

.2 

716.1 

.2 

470.9 

.2 

350.8 

.2 

279.4 

.4 

708.8 

.4 

467.7 

.4 

349.0 

.4 

278.3 

.6 

701.5 

.6 

464.5 

.6 

347.2 

.6 

277.2 

.8 

694.4 

.8 

461.4 

.8 

345.5 

.8 

276.1 

40 


ENGINE    TESTS. 


Table  of 


(Continued). 


M.  E.  P. 

13750 

M.E.  P. 

13750 

M.E.  P. 

13750 

M.  E.  P. 

13750 

M.E.  P. 

M.E.  P. 

M.E.  P. 

M.E.  P. 

50.0 

275.0 

60.0 

229.2 

70.0 

196.4 

80.0 

171.9 

.2 

273.9 

.2 

228.4 

.2 

195.9 

.2 

171.4 

A 

272.8 

.4 

227.6 

.4 

195.3 

.4 

171.0 

.6 

271.7 

.6 

226.9 

.6 

194.7 

.6 

170.6 

.8 

270.6 

.8 

226.1 

.8 

194.2 

.8 

170.2 

51.0 

269.6 

61.0 

225.4 

71.0 

193.6 

81.0 

169.7 

.2 

268.5 

.2 

224.7 

.2 

193.1 

.2 

169.3 

.4 

267.5 

.4 

223.9 

.4 

192.5 

.4 

168.9 

.6 

266.4 

.6 

223.2 

.6 

192.0 

.6 

168.5 

.8 

265.4 

.8 

222.5 

.8 

191.5 

.8 

168.1 

52.0 

264.4 

62.0 

221.8 

72.0 

191.0 

82.0 

167.7 

.2 

263.4 

.2 

221.1 

.2 

190.4 

.2 

167.2 

.4 

262.4 

.4 

220.3 

.4 

189.9 

.4 

166.9 

.6 

261.4 

.6 

219.6 

.6 

189.4 

.6 

166.4 

.8 

260.4 

.8 

218.9 

.8 

188.9 

.8 

166.1 

53.0 

259.4 

63.0 

218.2 

73.0 

188.3 

83.0 

165.6 

.2 

258.4 

.2 

217.6 

.2 

187.8 

.2 

165.3 

.4 

257.5 

.4 

216.9 

.4 

187.3 

.4 

164.8 

.6 

256.5 

.6 

216.2 

.6 

186.8 

.6 

164.5 

.8 

255.5 

.8 

215.5 

.8 

186.3 

.8 

164.1 

54.0 

254.6 

64.0 

214.8 

74.0 

185.8 

84.0 

163.7 

.2 

253.6 

.2 

214.2 

.2 

185.3 

.2 

163.3 

.4 

252.7 

.4 

213.5 

.4 

184.8 

.4 

162.9 

.6 

2518 

.6 

212.8 

.6 

184.3 

.6 

162.5 

.8 

250.9 

.8 

212.2 

.8 

1838 

.8 

162.1 

55.0 

250.0 

65.0 

211.5 

75.0 

183.3 

85.0 

161.7 

.2 

249.1 

.2 

210.9 

.2 

182.8 

.2 

161.4 

.4 

248.2 

.4 

210.2 

.4 

182.3 

.4 

161.0 

.6 

247.3 

.6 

209.6 

.6 

181.9 

.6 

Io0.6 

.8 

246.4 

.8 

208.9 

.8 

181.4 

.8 

160.2 

56.0 

245.5 

66.0 

208.3 

76.0 

180.9 

86.0 

159.9 

.2 

244.6 

.2 

207.7 

.2 

180.4 

.2 

159.5 

.4 

243.8 

.4 

207.1 

.4 

180.0 

.4 

159.1 

.6 

242.9 

.6 

206.4 

.6 

179.5 

.6 

158.7 

.8 

242.1 

.8 

205.8 

.8 

179.0 

.8 

158.4 

57.0 

241.2 

67.0 

205.2 

77.0 

178.6 

87.0 

158.0 

.2 

240.4 

.2 

204.6 

.2 

178.1 

.2 

157.7 

.4 

239.5 

.4 

204.0 

.4 

177.6 

.4 

157.3 

.6 

238.7 

.6 

203.4 

.6 

177.2 

.6 

157.0 

.8 

237.8 

.8 

202.8 

.8 

176.7 

.8 

156.6 

58.0 

237.0 

68.0 

202.2 

78.0 

176.8 

88.0 

156.2 

.2 

236.2 

.2 

201.6 

•2 

175.8 

.2 

155.9 

.4 

235.4 

.4 

201.0 

.4 

175.4 

.4 

155.5 

.6 

234.6 

.6 

200.4 

.6 

174.9 

.6 

155.2 

.8 

233.8 

.8 

199.8 

.8 

174.5 

.8 

154.8 

59.0 

2330 

69.0 

199.3 

79.0 

174.1 

89.0 

154.5 

.2 

232.2 

.2 

198.7 

.2 

173.6 

.2 

154.1 

.4 

231.4 

.4 

198.1 

.4 

173.2 

.4 

153.8 

.6 

230.7 

.6 

197.6 

.6 

172.7 

.6 

153.5 

.8 

229.9 

.8 

197.0 

.8 

172.3 

.8 

153.1 

HOW   THE    TESTS    WERE    CONDUCTED. 


41 


Table  of 


M.  Mi. 


(Concluded). 


M.  E.P. 

13750 
M.E.  P. 

M.E.  P. 

13750 

M.E.  P. 

13750 
M.E.  P. 

M.E.  P. 

13750 

M.  E.P. 

M.  E.  P. 

90.0 

152.8 

97.6 

140.9 

126 

109.13 

164 

83.84 

.2 

152.4 

.8 

140.6 

7 

108.27 

165 

83.33 

.4 

152.1 

98.0 

140.3 

8 

107.42 

6 

82.83 

.6 

151.7 

.2 

140. 

9 

106.59 

7 

82.34 

.8 

151.4 

.4 

139.7 

130 

105.77 

8 

81.85 

91.0 

151.1 

.6 

139.4 

1 

104.96 

9 

81.36 

.2 

150.8 

.8 

139.1 

2 

104.17 

170 

80.88 

.3 

150.5 

99.0 

138.9 

3 

103.38 

1 

80.41 

.6 

150.1 

2 

138.6 

4 

102.61 

2 

79.94 

.8 

149.8 

A 

138.3 

135 

101.85 

3 

79.48 

92.0 

149.5 

.6 

138. 

6 

101.10 

4 

79.02 

.2 

149.2 

.8 

137.8 

7 

100.36 

175 

78.57 

.4 

148.8 

100 

137.5 

8 

99.64 

6 

7813 

.6 

148.5 

1 

136.14 

9 

98.92 

7 

77.68 

.8 

148.2 

2 

134.8 

140 

98.21 

8 

77.25 

93.0 

147.9 

3 

133.5 

1 

97.52 

9 

76.82 

.2 

147.5 

4 

132.21 

2 

96.83 

180 

76.39 

.4 

147.2 

105 

130.95 

3 

96.15 

1 

75.97 

.6 

146.9 

6 

129.71 

4 

95.49 

2 

75.55 

.8 

146.6 

7 

128.5 

145 

94.83 

3 

75.14 

94.0 

146.3 

8 

127.31 

6 

94.18 

4 

74.73 

.2 

146. 

9 

126.15 

7 

93.54 

185 

74.32 

.4 

145.6 

110 

125. 

8 

92.91 

6 

73.93 

.6 

145.3 

1 

123.88 

9 

92.28 

7 

73.53 

.8 

145. 

2 

122.77 

150 

91.67 

8 

73.14 

95.0 

144.7 

3 

121.68 

1 

91.06 

9 

72.75 

.2 

144.4 

4 

120.61 

2 

90.46 

190 

72.37 

.3 

144.1 

115 

119.57 

3 

89.87 

! 

71.99 

.6 

143.8 

6 

118.54 

4 

89.29 

2 

71.62 

.8 

143.5 

7 

117.52 

155 

88.71 

3 

71.25 

96.0 

143.2 

8 

116.53 

6 

88.14 

4 

70.88 

.2 

142.9 

9 

115.55 

7 

87.59 

195 

70.51 

.4 

142.6 

120 

114.58 

8 

87.03 

6 

70.15 

.6 

142.3 

1 

113.64 

9 

86.48 

7 

69.80 

.8 

142. 

2 

112.71 

160 

85.94 

8 

69.44 

97.0 

141.7 

3 

111.79 

1 

85.40 

9 

69.10 

.2 

141.4 

4 

110.89 

2 

84.88 

200 

68.75 

.4 

141.2 

125 

110. 

3 

84.36 

PART    II. 


FEED-WATEK   TESTS. 

SIMPLE   ENGINES. 

[These  engines  are  all  horizontal,  unjacketed,  and  of  the  automatic  cut-off 
type,  with  fly-ball  governor,  unless  otherwise  specified.] 


4:"! 


ENGINE   No.  1. 

Simple  Non- Condensing. 

Kind  of  engine Four-valve  (Corliss) 

Number  of  cylinders .»*....  '1 

Diameter  of  cylinder      .     ...   J    ./ :. '  '.     ....  23         in. 

Diameter  of  piston-rod 3*         in. 

Stroke  of  piston ''.,'     .     ;:C";  5           ft- 

Clearance ..........  2*           % 

H.  P.  constant  for  1  Ib.  m.  e.  p.  one  revolution  per  min.  .1247 

Inside  diameter  of  steam  pipe 7           in. 

Inside  diameter  of  exhaust  pipe    .     .     »; 8           in. 

Condition  of  valves  and  pistons  regarding  leakage  .     .    „  Practically  tight 

Data  and  Results  of  Feed- Water  Test,  Engine  No.  1. 

Character  of  steam Ordinary 

Duration  .     „ 5.75     hrs. 

Weight  of  feed-water  consumed 48,741           Ibs. 

Feed-water  consumed  per  hour 8,477           Ibs. 

Pressure  in  steam  pipe  above  atm 72.3       Ibs. 

Mean  effective  pressure 33.08      Ibs. 

Revolutions  per  minute    .     .     .     .     .     .     . 74.7 

Indicated  horse-power      ....     .;...     .  V.     ....  305.2    H.  P. 

Feed-water  consumed  per  I.  H.  P.  per  hour .  27.77      Ibs. 

Measurements  based,  on  Sample  Diagrams. 

Initial  pressure  above  atmosphere 72.8      Ibs. 

Steam-pipe  pressure  above  atmosphere 73.6      Ibs. 

Cut-off  pressure  above  zero       „     .'    ..•_ .  66.5      Ibs. 

Release  pressure  above  zero .  24.3      Ibs. 

Mean  effective  pressure 33. 12    Ibs. 

Back  pressure  at  mid  stroke  above  atmosphere '        2.8      Ibs. 

Proportion  of  stroke  completed  at  cut-off .367 

Steam  accounted  for  at  cut-off  ..„..- 23.32    Ibs. 

Steam  accounted  for  at  release 23.66    Ibs. 

Proportion  accounted  for  at  cut-off .84 

Proportion  accounted  for  at  release .852 

Engine  No.  1  is  supplied  with  steam  in  part  from  a  number  of 
vertical  boilers,  and  in  part  from  a  single  boiler  of  the  horizontal 
return  tubular  type.  The  mixed  steam  showed  no  superheat- 
ing, though  probably  commercially  dry.  The  valves  and  pistons 
were  all  fairly  tight.  The  load  consisted  of  cotton  machinery. 

On  another  occasion  two  tests  were  made  on  this  engine,  the 
first  with  ordinary  steam  as  above,  and  the  second  with  super- 
heated steam,  the  horizontal  boiler  in  the  latter  case  being  out 
of  service.  The  principal  data  and  results  were  as  follows  : 

45 


ENGINE    TESTS. 


TEST. 
CHARACTER  OF  STEAM. 

No.  \b. 
ORDINARY. 

NO.  Ic. 
SUPERHEATED 

82°. 

Mean  effective  pr6ssur6                                  Ibs 

34  46 

35  07 

Proportion  of  stroke  completed  at  cut-off 

.375 

.392 

Feed-water  consumed  per  I.  H    P.  per 

hour    ........          .     Ibs. 

29.34 

26.83 

Steam  accounted  for  at  cut-off       .          .     Ibs. 

24.6 

25.42 

Steam  accounted  for  at  release      .          .     Ibs. 

25.26    ' 

24.15 

Proportion  accounted  for  at  cut-off     ~   . 

.839 

.947 

Proportion  accounted  for  at  release     .    ... 

.861 

.900 

The  marked  effect  of  superheating  is  indicated  by  comparing 
these  two  tests.  By  superheating  the  steam  82  degrees  the  con- 
sumption of  feed-water  per  I.  H.  P.  per  hour  was  reduced  about 
9  per  cent.  A  feature  in  these  results  is  the  effect  upon  the 
steam  accounted  for  by  the  indicator.  It  increases  between  cut- 
off and  release  from  24.6  pounds  to  25.26  pounds  when  ordi- 
nary steam  is  used,  whereas  the  contrary  effect  is  produced 
under  the  influence  of  the  superheating,  the  quantity  falling 
from  25.42  pounds  to  24.15  pounds. 

ENGINE  No.  1 


Head  End 


Crank  End 


-60 


-40 


-20 


-   O 


-60 


-40 


-20 


ENGINE    No.  2. 

Simple  Non- Condensing. 

Kind  of  engine Four-valve  (Corliss) 

Number  of  cylinders 1 

Diameter  of  cylinder 28.5        in. 

Diameter  of  piston-rod 4           in. 

Stroke  of  piston 59.5        in. 

Clearance 3             % 

H.  P.  constant  for  1  Ib.  m.  e.  p.  one  revolution  per  min.  .1898 

Inside  diameter  of  steam  pipe 8           in. 

Condition  of  valves  and  piston  regarding  leakage     .     .     .  Fairly  tight. 

Data  and  Eesults  of  Feed-Water  Test,  Engine  No.  2. 

Character  of  steam .     .,  '  .  Ordinary 

Duration .'•    . .  6.08       hr. 

Weight  of  feed-water  consumed   .     .     .     ..;.'...     .     .     .  79,467           Ibs. 

Feed-water  consumed  per  hour 13,070           Ibs. 

Pressure  in  steam  pipe  above  atmosphere J._.  101           Ibs. 

Mean  effective  pressure 41.18     Ibs. 

Revolutions  per  minute 64.-8 

Indicated  horse-power 506.5    H.  P. 

Feed-water  consumed  per  I.  H.  P.  per  hour    .     .     .     .     .     .  25.8        Ibs. 

Measurements  based  on  Sample  Diagrams. 

Initial  pressure  above  atmosphere '.  91          'bs. 

Cut-off  pressure  above  zero , .  82.9      Ibs. 

Release  pressure  above  zero ......  26.3       Ibs. 

Mean  effective  pressure ..'..,.     .     .     .  41.18    Ibs. 

Back  pressure  at  mid -stroke  above  atmosphere 4.2      Ibs. 

Proportion  of  stroke  completed  at  cut-off .315 

Steam  accounted  for  at  cut-off 21.06    Ibs. 

Steam  accounted  for  at  release 21.35    Ibs. 

Proportion  accounted  for  at  cut-off .817 

Proportion  accounted  for  at  release. .828 

Engine  No.  2  is  supplied  with  steam  from  water  tube  boilers. 
A  calorimeter  test  showed  less  than  one  per  cent  of  moisture. 
The  steam  valves  and  piston  were  tight.  The  exhaust  valves 
leaked  a  small  amount.  The  load  was  that  of  a  cotton-mill. 


47 


ENGINE  No.  2 


Head  End 


-100 
-80 
-60 
-40 
-20 
-  0 


Crank  End 


ENGINE    No.  3. 


Simple  Condensing. 
Kind  of  engine  .     .     .     .'    .     .     .     .     .     .     .     .     .     .     .     Four-valve  (Corliss) 

Number  of  cylinders  .............  2 


Diameter  of  each  cylinder 

Diameter  of  piston-rod 

Stroke  of  each  piston 

Clearance ,     i 

H.  P.  constant  for  1  Ib.  m.  e.  p.  one  revolution  per  rnin. 

Inside  diameter  of  steam  pipe 

Inside  diameter  of  exhaust  pipe         .     .'    » 

Condition  of  valves  and  pistons  regarding  leakage   .     .     . 

Data  and  Results  of  Feed- Water  Tests,  Engine  No.  3. 


in. 
in. 

ft. 


20i 
4 

3  Of 

fO 

.1532 
8  in. 

8  in. 

Fairly  tight. 


CONDITIONS  AS  TO  USE  OF  CONDENSER. 

TEST  A. 

ALL- 
CONDENSING. 

TEST  B. 

THREE  ENDS  CON- 
DENSING, ONE  END 
NON-CONDENSING. 

Character  of  steam    
Duration      ........ 
Weight  of  feed-water  consumed  . 
Feed-water  consumed  per  hour   . 
Pressure   in   steam    pipe     above 
atmosphere 

hrs. 
Ibs. 
Ibs. 

Ibs. 
in. 
Ibs. 

H.P. 

Ibs. 

Ordinary 
4.75 
21,185. 
4,460. 

67.2 
26.2 
22.79 
60.3 
210.5 

21.11 

Ordinary 
4.75 
24,671. 
5,194. 

69.1 
26.5 
24.79 
60.3 
229. 

22.68 

Vacuum  in  condenser    .... 
Mean  effective  pressure      .     .     . 
Revolutions  per  minute   -  ... 
Indicated  horse-power   .... 
Feed-  water  consumed  per  I.  H.  P. 
per  hour    

Measurements  based  on  Sample  Diagrams. 


Initial  pressure  above  atmosphere     Ibs. 

60.8 

64.1 

AVERAGE  OF 
THREE 
CONDENSING 
ENDS. 

NON- 
CON- 
DENSING 
END. 

Cut-off  pressure  above  zero     .     .     Ibs. 
Release  pressure  above  zero     .     .     Ibs. 
Mean  effective  pressure       .     .     .     Ibs. 
Back  pressure  at  mid-stroke  above 
or  below  atmosphere    .     .     .     Ibs. 
Proportion   of  stroke  completed 
at  cut-off                                       Ibs 

59.9 
9.3 
23.23 

11.9 
138 

63. 
10.5 
26.41 

-  12. 
.152 

63. 
13.5 
19.01 

+  1. 
.185 

Steam  accounted  for  at  cut-off     .     Ibs. 
Steam  accounted  for  at  release    .     Ibs. 
Proportion  accounted  for  at  cut- 
off   (average    for  the   whole 
engine)      
Proportion   accounted  for  at  re- 
lease 

13.85 
14.77 

.654 
697 

13.95 
14.59 

.6 

.7 

21.19 
24.06 

95 
48 

50  ENGINE    TESTS. 

Engine  No.  3  has  a  pair  of  cylinders  exhausting  into  a  jet 
condenser  operated  by  a  direct-connected  air-pump.  The  ex- 
haust passages  and  piping  are  arranged  so  as  to  run  one  end  of 
one  cylinder  non-condensing.  One  test  was  made  running  both 
cylinders  condensing,  and  one  test  running  three  ends  condens- 
ing and  one  end  non-condensing.  The  engine  is  supplied  with 
steam  from  horizontal  return  tubular  boilers.  The  quality  of 
the  steam  was  not  tested,  but  it  was  probably  commercially  dry. 
One  steam  valve  and  the  exhaust  valves  of  one  cylinder  showed 
some  leakage.  The  remaining  valves,  and  the  pistons,  were 
fairly  tight.  The  engine  was  employed  in  driving  several  man- 
ufactories working  in  connection  with  water-wheels. 

The  loss  in  steam  due  to  running  one  end  of  the  cylinder 
non-condensing  is  about  1%.  The  gain  in  fuel  that  would 
be  produced  by  utilizing  the  exhaust  steam  from  this  end  for 
heating  feed-water  for  the  boilers,  assuming  that  it  increases 
the  temperature  from  60  to  210  degrees,  is  sufficient  to  cover 
the  increased  steam  consumption  and  leave  a  net  fuel  saving  of 
some  7. 


ENGINE  No.  3  a 


R,H.  Cyl.  Crank  End 


—60 

—  40 
—20 

—  0 

—  10 

—  60 

—  40 

—  20 

—  0 

—  10 


60- 
40  — 
20  — 

0— 
10- 

60- 
40- 
20— 

0- 
10- 


L.H.  Cyl.  Head  End 


L,H.  Cyl.  Crank  End 


ENGINE  No.  3b 


R.H.  Cyl.  Head  End 


R.H.  Cyl.  Crank  End 


-60 

-40 
-20 

-  0 

10 

-60 

-40 
-20 

—  0 

—  10 


60- 


40- 


20- 


O-1 


L,H.CyI.  Head  End 


60- 


40- 


20- 


0- 
10- 


L.H.  Cyl.  Crank  End 


ENGINE  No.  4. 


Simple  Condensing. 

Kind  of  engine      ,     ,     , 

Number  of  cylinders , 

Diameter  of  cylinder 

Diameter  of  piston-rod  ....     .     .     .     ,  V. 

Stroke  of  piston .     .     ,     ...     . 

Clearance 

H.P.  Constant  for  one  Ib.  m.e.p.,  one  rev.  per  minute 
Inside  diameter  of  steam  pipe  ....  .  ,  '.'•-.-» 
Inside  diameter  of  exhaust  pipe  .  .  .  .  »  .  .  .. 
Condition  of  valves  and  piston  regarding  leakage  . 


Four-valve  (Corliss) 
1 

34.2  ins. 
4i    ins. 

5  ft. 
3         % 

.2764 

6  ins. 

7  ins. 
Fairly  tight. 


Data  and  Results  of  Feed  Water  Test,  Engine  No.  4. 
Character  of  steam Superheated  25 


Duration 

Weight  of  feed-water  consumed  .... 
Feed-water  consumed  per  hour  .... 
Pressure  in  steam  pipe  above  atmosphere  . 

Vacuum  in  condenser 

Mean  effective  pressure 

Rev.  per  min 

Indicated  horse-power 

Feed-water  consumed  per  I.  H.  P.  per  hour 


deg. 
hra. 

Ibs. 

Ibs. 

Ibs. 


10.8 
125,420 
11,613 

83 

24.8 

35.53 

53.3 
523.43  H.  P. 

22.19     Ibs. 


ins. 
Ibs. 


Measurements  Based  on  Sample  Diagrams :  — 


Initial  pressure  above  atmosphere    . 
Steam-pipe  pressure  above  atmosphere 


76.1  Ibs. 
83     Ibs. 


HEAD  END. 

NON-CONDENSING  . 

CRANK  END. 
CONDENSING. 

Cut-off  pressure  above  zero 

Ibs. 

71.9 

76.7 

Release  pressure  above  zero 

Ibs. 

17.5 

18.1 

Mean  effective  pressure 

Ibs. 

28.22 

41.88 

Back  pressure  at  mid-stroke,  above  or 

below  atmosphere 

Ibs. 

+  2.1 

—  11.7 

Proportion  of  stroke  completed  at  cut-off 

Ibs. 

.237 

.230 

Steam  accounted  for  at  cut-off   . 

Ibs. 

18.79 

15.18 

Steam  accounted  for  at  release  . 

Ibs. 

18.75 

15.43 

Proportion    accounted    for    at    cut-off 

(average  of  two  ends)  

Ibs. 

.766 

Proportion  accounted  for  at  release 

Ibs. 

.77 

OF   THE 


54 


ENGINK   TESTS. 


Engine  No.  4  exhausts  into  a  jet  condenser  with  direct-con- 
nected air-pump.  One  end  is  run  condensing,  and  the  other 
end  non-condensing.  The  boilers  are  of  the  vertical  type, 
which  superheat  the  steam.  Steam  was  supplied  for  other 
purposes  than  power,  and  the  amount  thus  used  was  deter- 
mined and  allowed  for.  There  was  slight  leakage  of  the  steam 
valves.  The  exhaust  valves  and  piston  were  practically  tight. 
The  load  was  that  of  a  cotton  mill. 


ENGINE  No.4 


80- 


60- 


40— 


20- 


Head  End 


60- 


40— 


20- 


O- 
10- 


Crank  End 


ENGINE    No.  5. 

Simple  Condensing. 

Kind  of  engine     .  ....'.     Four-valve  (Corliss) 

Number  of  cylinders .  2 

Diameter  of  each  cylinder 32.5        ins. 

Diameter  of  each  piston-rod    .  \     .......  4?          ins. 

Stroke  of  each  piston ..."...,".  4.5          ft. 

Clearance 3               % 

H.P.  Constant  for  one  Ib.  M.E.P.  one  rev.  per  min.  .     .  .4484 

Inside  diameter  of  steam-pipe 7           ins_ 

Condition  of  valves  and  pistons  regarding  leakage  .     .     .  Some  leakage. 

Data  and  Results  of  Feed-  Water  Test,  Engine  No.  5. 

Character  of  steam      , .  .              Ordinary 

Duration 5.55     nrs. 

Weight  of  feed-water  consumed    .     .     .     .     .     ....     .  100,253           Ibs. 

Feed-water  consumed  per  hour     .     .     .     .     .     .....  18,063           Ibs. 

Pressure  in  steam  pipe 71.1        ibs. 

Vacuum  in  condenser      .          26.2         in. 

Mean  effective  pressure 32.41      Ibs. 

Re  volutions  per  minute 47.3 

Indicated  horse-power .  687.39  H.  P. 

Feed-water  consumed  per  I.  H.  P.  per  hour    .     .     „     .     .     .  26.28      Ibs. 

Measurements  Based  on  Sample  Diagrams. 


CONDENSING 
CYLINDER. 


NON- 
CONDENSING 
CYLINDER. 


Initial  pressure  above  atmosphere     .     .     .     Ibs. 

Cut-off  pressure  above  zero Ibs. 

Release  pressure  above  zero Ibs. 

Mean  effective  pressure  .    • Ibs. 

Back  pressure  at  mid-stroke,  above  or  be- 
low atmosphere Ibs. 

Proportion  of  stroke  completed  at  cut-off  . 

Steam  accounted  for  at  cut-off      ....     Ibs. 

Steam  accounted  for  at  release     ....     Ibs. 

Proportion  accounted  for  at  cut-oft  (aver- 
age for  whole  engine) 

Proportion  accounted  for  at  release  . 


70.3 
63.5 
20.1 
39.54 

-9.4 

.298 
16.78 
17.36 


.784 
.813 


65.2 
63. 
20. 
26.2 

+  4.9 

.308 
24.47 
25.39 


Engine  No.  5  has  a  pair  of  cylinders,  one  of  which  exhausts 
into  a  jet  condenser,  with  direct-connected  air-pump,  and  the 
other  is  non-condensing.  Steam  is  furnished  from  cylinder 

55 


56  ENGINE    TESTS. 

boilers,  and  it  appeared  to  be  commercially  dry.  A  small 
amount  was  used  for  other  purposes  than  running  the  engine, 
but  the  quantity  thus  consumed  was  determined,  and  allow- 
ance made  for  it.  The  valves  and  piston  of  one  cylinder 
showed  some  leakage ;  those  of  the  other  cylinder  were  fairly 
tight.  The  load  consisted  of  cotton  machinery. 


ENGINE  No.  5 


R.H.Cyl.  Head  End 


60- 


40- 


20- 


0-1 


L.H.Cyl.  Head  End 


L.H.Cyl.  Crank  End 


-60 


_40 


-20 


•—   0 


ENGINE    No.  6, 

Simple  Condensing. 

Kind  of  engine Four-valve  (Corliss) 

Number  of  cylinders 2 

Diameter  of  each  cylinder ...  26j          in. 

Diameter  of  each  piston  rod 3f         iu. 

Stroke  of  each  piston      .                5            ft. 

Clearance •    ..     .-" 3             ^ 

H.  P.  Constant  for  one  Ib.  m.  e.  p.  one  rev.  per  minute,  .3254 

Inside  diameter  of  steam  pipe 8           in. 

Inside  diameter  of  exhaust  pipe  .     .     ,     .     .....  10           in. 

Condition  of  valves  and  pistons  regarding  leakage  .     .     .  Some  leakage. 

Data  and  Results  of  Feed-Water  Test,  Engine  No.  6. 

Character  of  steam i.          .  ,  .  Ordinary 

Duration  .     .     .     .     .     .     ,     .     .     .  •   ,     .     .     .     .     .     .     .  5.08      hrs. 

Weight  of  feed-water  consumed 71,150          Ibs. 

Feed-water  consumed  per  hour .     .  14,006          Ibs. 

Pressure  in  steam  pipe     .     :     .     .     ».   .    '.     .     .     .    '.     .     .  84.4       Ibs. 

Vacuum  in  condenser       .     .     ,     ...     .     .     .     .     .     '.     .  27.3        in. 

Mean  effective  pressure    .     .     .     .     .     .     ,     .     .     ...     .  36.73    Ibs. 

Eevolutions  per  minute    .     .     .    _,-  . .     .          .     .....     .  51.1 

Indicated  horse-power      .     .     .     ...     .     ....     .    v    .  610.74  H.  P. 

Feed-water  consumed  per  I.  H.  P.  per  hour     .     .     .  '  .     .     .  22.95     Ibs. 


Measurements  based  on  Sample  Diagrams. 


THREE 

ENDS 

CONDENSING. 


NON- 
CONDENSING 
END. 


Initial  pressure  above  atmosphere     .     .     .     Ibs. 

Cut-off  pressure  above  zero Ibs. 

Kelease  pressure  above  zero Ibs. 

Mean  effective  pressure Ibs. 

Back  pressure  at  mid  stroke,  above  or  be- 
low atmosphere Ibs. 

Proportion  of  stroke  completed  at  cut-off  . 

Steam  accounted  for  at  cut-off     ....     Ibs. 

Steam  accounted  for  at  release    ....     Ibs. 

Proportion  accounted  for  at  cut-off  (aver- 
age for  whole  engine 

Proportion  accounted  for  at  release  (aver- 


77.3 
74.6 
17.2 
39.46 

10.2 

.233 
15.81 
15.56 


.757 


.754 


76. 
73.8 
20.4 
30.03 

4.5 

.271 
22.12 
22.63 


Engine  No.  6  has  a  pair  of  cylinders  exhausting  into  a  jet 
condenser  with  direct-connected  air-pump.     One  cylinder  was 

58 


ENGINE   No,    6.  59 

run  condensing,  and  one  end  of  the  other  cylinder  non-con- 
densing. Steam  is  supplied  from  sectional  boilers  with  large 
drum,  and  from  all  appearances  it  was  in  a  commercially  dry 
condition.  Both  pistons  showed  some  leakage,  but  the  valves 
were  all  fairly  tight.  The  load  consisted  of  cotton  machinery. 


ENGINE  No.  6 


R.H.  Cyl,  Head  End 


—60 


40- 


20- 


10— ' 


ENGINE    No.  7. 

Simple  Non-Condensing. 

Kind  of  engine .  ^ .     .     .     .     Four-valve  (Corliss) 

Number  of  cylinders 1 

Diameter  of  cylinder 26i3s        iu. 

Diameter  of  piston  rod 31         in. 

Stroke  of  piston    .     .     ....     .     .     •     •     ..:....  4            ft. 

Clearance .     .     .' 3             % 

H.  P.  constant  for  one  Ib.  in.  e.  p.  one  revolution  per  min.  .1285 

Inside  diameter  of  steam  pipe 6           in. 

Condition  of  valves  and  piston  regarding  leakage    .     .     .  Some  leakage. 

Data  and  Results  of  Feed-Water  Test,  Engine  No.  7. 

Character  of  steam '.  Ordinary 

Duration 5.1  hrs. 

Weight  of  feed-water  consumed 34,386  .  Ibs. 

Feed-water  consumed  per  hour 6,742  Ibs. 

Pressure  in  steam  pipe  above  atmosphere    .     .     .     .-.',.     .          80.5  Ibs. 

Mean  effective  pressure    .     .     .     .     .     .     .     ....     .     .          27.82  Ibs. 

Revolutions  per  minute C.  •          ^4.7 

Indicated  horse-power .  .     232.3  H.  P. 

Feed- water  consumed  per  I.  H.  P.  per  hour 29.03  Ibs. 

Measurements  based-  an-  Sample  Diagrams. 

Initial  pressure  above  atmosphere .,  79.6      Ibs. 

Cut-off  pressure  above  zero 76.6      Ibs. 

Release  pressure  above  zero 19.6      Ibs. 

Mean  effective  pressure ;....,,.  27.3      Ibs. 

Back  pressure  at  mid  stroke  above  atmosphere 5.4      Ibs. 

Proportion  of  stroke  completed  at  cut-off  .     .     .     .     .     .     .     .  .237 

Steam  accounted  for  at  cut-off      .     ...     .     '.     ....     ...  21.77    Ibs. 

Steam  accounted  for  at  release     .     .     .     ,     .     .     .     .     .     .     .  23.31    Ibs. 

Proportion,  accounted  for  at  cut-off  .     .     .     .     .7'  .    T~  7_  .  .75 

Proportion  accounted  for  at  release .803 

Engine  No.  7  is  supplied  with  steam  from  horizontal  return 
tubular  boilers,  presumably  in  a  commercially  dry  condition. 
The  valves  were  fairly  tight,  but  there  was  considerable  leakage 
of  the  piston.  The  load  consisted  of  cotton  machinery. 


(51 


80-, 


ENGINE  No.  7 


60- 


Head  End 


40- 


20- 


80-i 


60- 


Crank  End 


40- 


20- 


o-1 


ENGINE    No.  S. 


Simple  Condensing. 


Kind  of  engine 

Number  of  cylinders 

Diameter  of  cylinder 

Diameter  of  piston  rod 

Stroke  of  piston 

Clearance     

H.P.  constant  for  one  Ib.  m.e.p.  one  rev.  per  min. 
Condition  of  valves  and  piston  regarding  leakage    . 

Data  and  Results  of  Feed-Water  Tests. 


Four-valve  (Corliss) 

1 


ins. 

ins. 

ft. 


30 

41 
6 
3  % 

.2543 
Fairly  tight. 


CONDITIONS  AS  TO  PRESSURE. 

TEST  A. 
ORDINARY. 

TEST  B. 
EXTRA. 

Character  of  steam   

Superhtd.  37° 

Superhtd.  37° 

Duration     

hrs. 

5.667 

5.167 

Weight  of  feed-water  consumed  .... 

Ibs. 

40,281. 

34,984. 

Feed-water  consumed  per  hour  .... 

Ibs. 

7,104. 

6,771. 

Pressure  in  steam-pipe  above  atmosphere  . 

Ibs. 

53.1 

68.2 

Vacuum  in  condenser    

ins. 

29.7 

29.8 

Mean  effective  pressure      

Ibs. 

26.63 

26.3 

Revolutions  per  minute      

54.1 

54.1 

Indicated  horse-power  

H.P. 

366.4 

361.8 

Feed-water  consumed  perl.H.P.  per  hour 

Ibs.                19.39 

18.71 

Measurements  based  on  Sample  Diagrams. 


CONDITIONS  AS  TO  PRESSURE. 

TEST  A. 
ORDINARY. 

TEST  B. 
EXTRA. 

Initial  pressure  above  atmosphere    .     .     . 
Cut-off  pressure  above  zero 

Ibs. 
Ibs 

46.5 
47  0 

61.5 
58  6 

Release  pressure  above  zero    
Mean  effective  pressure 

Ibs. 
Ibs 

11.1 
26  84 

9.8 
26  39 

Back  pressure  at  mid-stroke  below  atm. 
Proportion  of  stroke  completed  at  cut-off  . 
Steam  accounted  for  at  cut-off    .... 
Steam  accounted  for  at  release    .... 
Proportion  accounted  for  at  cut-off  . 
Proportion  accounted  for  at  release 

Ibs. 
Ibs. 
Ibs. 
Ibs. 

—  12.4 
.247 
15.89 
15.19 
.819 
.783 

—  12.4 
.165 
13.98 
13.72 

.747 
.733 

Engine  No.  8  exhausts  into  a  jet  condenser  with  direct-con- 
nected air-pump.  Steam  is  supplied  through  a  12-inch  pipe, 
160  feet  in  length,  from  vertical  boilers  which  superheat.  The 
amount  of  superheating  at  the  boilers  on  the  test  was  67  degrees. 

63 


64  ENGINE    TESTS. 

It  was  subsequently  found  that  the  loss  of  temperature  between 
the  boilers  and  the  throttle  valve  was  60  degrees ;  so  that  the 
steam  entering  the  cylinder  was  still  in  a  slightly  superheated 
condition.  The  valves  and  pistons  were  fairly  tight.  The  load 
consisted  of  cotton  machinery. 

Advantage  was  taken  of  the  comparatively  light  load  to  make 
a  trial  of  the  engine  under  two  pressures.  The  other  conditions 
of  running  were  the  same  in  both  cases. 

It  appears  that  the  increase  of  pressure  from  53  pounds  to 
68  pounds  was  attended  by  a  reduction  in  the  steam  consump- 
tion amounting  to  nearly  four  per  cent.  There  is  a  marked 
increase  in  the  cylinder  condensation  (and  leakage),  with  the 
shortening  of  the  cut-off  and  increase  of  pressure. 


ENGINE  No.  8  a 


40- 


20- 


40- 


20- 


Head  End 


60—, 


ENGINE  No.  8b 


40- 


Head  End 


20- 


0— 
10— 

60- 
40- 
20- 

0— 
10- 


CrankEnd 


ENGINE    No.  9, 


Simple  Condensing. 

Kind  of  engine      ...... 

Number  of  cylinders 

Diameter  of  each  cylinder 

Diameter  of  each  piston  rod 

Stroke  of  each  piston 

Clearance „ 

H.P.  constant  for  one  Ib.  m.e.p.  one  rev.  per  minute  . 

Inside  diameter  of  steam  pipe 

Condition  of  valves  and  pistons  regarding  leakage  . 


Four  valve  (Corliss) 

2 

30i  ins. 
41  ft. 
6  ft. 

3  % 

.515 

8          ins. 
Some  leakage. 


Data  and  Results  of  Feed- Water  Tests. 


TEST  A. 

TEST  B. 

THREF 

CONDITIONS  AS  TO  USE  OF  CONDENSER. 

ALL 
CON- 

FOURTHS 
Cox 

DENSING 

DENSING. 

Character  of  steam  .     .     .-^.     .     .     .     . 

Supd.  24° 

Super  htd.  24° 

Duration                                                .    -, 

hrs 

5  1 

5  37 

Weight  of  feed-water  consumed  .     .''.'. 

Ibs. 

70,565. 

83,060. 

Feed-water  consumed  per  hour  .     ... 

Ibs. 

13,838. 

15,4(57. 

Pressure  in  steam  pipe  above  atmosphere  . 

Ibs. 

70.8 

73.4 

Vacuum  in  condenser    *     . 

ms. 

26.7 

26.7 

Mean  effective  pressure                               » 

Ibs 

32  00 

31  44 

Revolutions  per  minute                          - 

46 

46 

Indicated  horse-power  .                     ... 

H  P 

758  27 

758  10 

Feed-water  consumed  per  I.  H.P.  per  hour 

Ibs. 

18.25 

20.4 

Measurements  based  on  Sample  Diagrams. 


CONDITIONS  AS  TO  USE  OF  CONDENSER. 

NON- 
CONDENS- 
ING 
•END. 

THREE 
ENDS 
CONDENS- 
ING. 

Initial  pressure  above  atmosphere      .     .     .  Ibs. 
Cut-off  pressure  above  zero       Ibs. 
Release  pressure  above  zero     Ibs. 
Mean  effective  pressure  .     ._..;.     .     .     .     .  Ibs. 
Back  pressure  at  mid-stroke,  above  or  below 
atmosphere                                               Ibs. 

67.7 
70.4 
12.9 
32.10 

—  11  5 

70.7 
69.6 
17.2 
26.11 

+  4  0 

67.8 
72.5 
13.9 
34.54 

11  5 

Proportion  of  stroke  completed  at  cut-off    . 
Steam  accounted  for  at  cut-off       ....  Ibs. 
Steam  accounted  for  at  release     ....  Ibs. 
Proportion  accounted  for  at  cut-off   . 
Proportion  accounted  for  at  release  .     .     . 

.185 
14.97 
14.52 
.82 
.796 

.247 

21.94 
21.88 

.8, 
.8 

.202 
14.45 
14.47 
56 

67 

Engine  No.  9  has  a  pair  of  cylinders  exhausting  into  a  jet 
condenser  with  direct-connected  air-pump.  Steam  is  supplied 
in  a  slightly  superheated  condition  from  vertical  boilers. 
Arrangements  are  made  so  that  one  end  of  one  cylinder  can  be 
run  non-condensing.  One  test  was  made  with  this  end  operat- 
ing non-condensing,  and  another  when  the  whole  engine  was 
running  condensing.  The  exhaust  valves  and  steam  valves  of 
one  cylinder  were  fairly  tight.  The  steam  valves  of  the  other 
cylinder  and  the  pistons  of  both  cylinders  showed  some  leakage. 
The  load  consisted  of  cotton  machinery. 

The  loss  of  steam  due  to  running  one  end  of  one  cylinder 
non-condensing  is  2.15  pounds  per  I.  H.  P.  per  hour,  or  11.8% 
of  the  quantity  required  when  running  condensing. 


ENGINE  No.  9  a 


60- 


R.H.Cyl.  Head  End 


ENGINE  No.Qb 


60- 


40- 


20- 


o-1 


60- 


j 
40  H 


20- 


o- 

10- 


RH.  Cyl.  Head  End 


R.H.Cyl.  Crank  End 


L.H.  Cyl.  Head  End 


-60 


-40 


ENGINE    No.   10. 


Double  Valve 

o 


Simple  Condensing  Engine. 

Kind  of  engine      ...          ......        /.     .     .     . 

Number  of  cylinders       .     .'  ."  •  .'    ....     / 

Diameter  of  each  cylinder  .     .     .     .  "  „     ..-'.'.     .     .     .     .     .  17               in. 

Diameter  of  each  piston  rod     .     .     ...     .........  2.75          in. 

Stroke  of  each  piston      .     .'._.'._ 24.2           in. 

Clearance     .     .     .     %.  --    .     .     .     .  ~ 2                 % 

H.  P.  Constant  for  one  Ib.  in.  e.  p.  one  rev.  per  minute       .     .  .  .0551  H.P. 

Inside  diameter  of  steam  pipe.    — ^    .-    .-..-.,-   ..-  ..,..-  ,.    ,     .--.-.  6               in. 

Condition  of  valves  and  pistons  regarding  leakage   .     .     .     .     .  Some. leakage 

Data  and  Results  of  Feed-  Water  Tests,  Engine  No.  10. 


CONDITIONS  AS  TO  USE  OF  CONDENSER. 

CONDENSING. 

XON- 
CONDENSING. 

Character  of  steam   .     .     .     .     .     .^  „-•'.' 

Superhtd.  16° 

Superhtd.  41° 

Duration     .     .     .  "  .     . 

hrs. 

5.7 

5.21 

Weight  of  feed-water  consumed  .... 

Ibs. 

39,299. 

41,415. 

Feed-water  consumed  per  hour  .... 

Ibs. 

6,895. 

7,952. 

Pressure  in  steam  pipe  above  atmosphere  . 

Ibs. 

79. 

75.9 

Vacuum  in  condenser    

ins. 

23.6 

Mean  effective  pressure 

Ibs. 

39.36 

36.82 

Revolutions  per  minute      .     .  '   .     ,  .  .     . 

154.7 

152.9 

Indicated  horse-power  I 

H.P. 

336.2 

310.1 

Feed-water  consumed  per  I.  H.P.  per  hour 

Ibs. 

20.51 

25.64 

i 

Measurements  based  on  Sample  Diagrams. 


CONDITIONS  AS  TO  USE  OF  CONDENSER. 

CONDENSING. 

NON- 
CONDENSING. 

Initial  pressure  above  atmosphere      .     .     . 

Ibs. 

74.5 

76.4 

Steam-pipe  pressure  above  atmosphere    . 

Ibs. 

78 

79 

Cut-off  pressure  above  zero  .     .     .  ~~.     T-  r 

Ibs. 

72.9 

72.8 

Release  pressure  above  zero      .     .....     . 

Ibs. 

19.7 

25.2 

Mean  effective  pressure    

Ibs. 

42.15 

37.43 

Back  pres.  at  mid  stroke  above  or  below  atm. 

Ibs. 

—  10.1 

+  1.0 

Proportion  of  stroke  completed  at  cut-off    . 

.262 

.337 

Steam  accounted  for  at  cut-off       .     .  -.,.'  .7 

Ibs. 

15.82 

20.78 

Steam  accounted  for  at  release       .     ... 

Ibs. 

15.53 

20.42 

Proportion  accounted  for  at  cut-off    . 

.771 

.811 

Proportion  accounted  for  at  release   .     .     . 

.757 

.795 

Engine  No.  10  has  a  pair  of  cylinders,  with  condenser  of 
the  siphon  type,  which  is  supplied  with  water  by  means  of  a 
belt  pump  operated  by  the  engine.  Ths  main  valves  are  bal- 

70 


ENGINE  No.    10.  71 

anced  slides.  The  cut-off  valve  rides  on  a  seat  in  the  interior 
of  the  main  value,  which  is  of  box  pattern.  The  cut-off  valve 
is  controlled  by  a  shaft  governor.  One  test  was  made  with 
the  engine  running  condensing,  and  one  running  non-condens- 
ing. Steam  is  furnished  by  superheating  vertical  boilers,  which 
are  190  feet  distant  from  the  throttle  valves,  the  connecting 
pipe  being  10  inches  in  diameter.  The  loss  of  temperature 
from  the  boilers  to  the  engine  amounted  to  54  degrees.  The 
pistons  and  cut-off  valves  were  practically  tight.  The  main 
valves  showed  some  leakage.  The  engine  worked  in  connec- 
tion with  water-wheels,  and  supplied  power  to  a  cotton-mill. 

From  these  results  it  appears  that  the  consumption  of  steam 
when  the  engine  was  run  condensing  was  5.13  Ibs.  per  I.  H.  P. 
per  hour  less  than  when  run  non-condensing,  or  20%. 

In  making  this  comparison  it  should  be  observed  that  there 
was  a  comparatively  poor  vacuum,  both  in  the  cylinders  and  in 
the  condenser,  which  acted  unfavorably  upon  the  condensing 
result ;  and  this  was  further  influenced  in  the  same  direction 
by  the  relatively  small  amount  of  superheating. 


ENGINE  No.lOa 


60- 
40- 
20- 

0- 
10- 

60- 
40— 
20- 


V 


R.H.Cyl.  Head  End 


J 


R.H.Cyl.  Crank  End 


60- 


40— 


20— 


60— 


40— 


ENGINE  No.  lOb 


80—1 


60  — 


40  — 


20— 


0 
80^ 


60- 
40— 
20- 

0- 
80 -, 

60- 
40- 
20- 


0-1 
80^ 


60  — 


40- 


20-^ 


0  — 


RH,  Cyl.  Head  End 


R.H.Cyl.  Crank  End 


L.H.Cyl.  Head  End 


L.H.  Cyl.  Crank  End 


OPTHK      '*? 

UNIVERSITY 


ENGINE    No.   1  1. 

Simple  Non-Condensing  Engine. 

Kind  of  engine     .     .     .     .     .     .     .     .     ...     .  - Four  valve 

Number  of  cylinders       .....     .....     .     . 1 

Diameter  of  cylinder     '..-...',.     .     .     .     .     ...     .     .161         ins. 

Diameter  of  piston  rod -.     .     .     .     . 21          ins. 

Stroke  of  piston 32  ins. 

Clearance    ....     .     .     .     .     .     _~  . .      4  % 

H.P.  constant  for  one  Ib.  in.  e.  p.  one  rev.  per  ruin 0346H.P. 

Inside  diameter  of  steam  pipe 5  in. 

Condition  of  valves  and  piston  regarding  leakage    .     .     .    Considerable  leakage 

Data  and  Results  of  Feed-Water  Test. 

Character  of  steam Ordinary 

Duration 5.47       hrs. 

Weight  of  feed-water  consumed    .     .     .     .     .    '.     .     .'  .     .  10,277            Ibs. 

Feed-water  consumed  per  hour 1,879            Ibs. 

Pressure  in  steam-pipe  above  atmosphere 61             Ibs. 

Mean  effective  pressure 18.19        Ibs. 

Revolutions  per  minute    .     .     .     .....     .     .     .     .     .     .  79.8 

Indicated  horse-power 50.2    I. H.P. 

Feed-water  consumed  per  I.  H.  P.  per  hour    .......  37.43        Ibs. 

Measurements  based  on  Sample  Diagrams. 

Initial  pressure  above  atmosphere 58.6      Ibs. 

Cut-off  pre  .sure  above  zero      .     .     .     .     ,     . 56.1      Ibs. 

Release  pressure  above  zero 16.7      Ibs. 

Mean  effective  pressure  .     .............  18.29    Ibs. 

Back  pressure  at  mid  stroke  above  atmosphere '.  1.1      Ibs. 

Proportion  of  stroke  completed  at  cut-off .234 

Steam  accounted  for  at  cut-off      .     .     .     .    '.     .     .'..'•_,...     .-,  21.52    Ibs. 

Steam  accounted  for  at  release     .     .  27.42    Ibs. 

Proportion  accounted  for  at  cut-off  ....  .575 

Proportion  accounted  for  at  release  . v  .     .  .......  •«.-.••*-.--.     .    ,.     /'  .732 

Engine  No.  11  is  controlled  by  a  shaft  governor.  It  lias 
piston  valves  provided  with  means  for  adjustment  to  take  up 
wear.  Steam  is  supplied  from  return  tubular  boilers,  probably 
in  a  commercially  dry  condition.  The  piston  and  one  steam 
valve  were  fairly  tight.  The  other  steam  valve  and  both  ex- 
haust valves  leaked.  The  engine  was  employed  in  driving  a 
machine-shop. 

The  effect  of  leakage,  low  pressure,  and  light  load  is  seen  in 
the  excessive  consumption  of  steam  shown  on  this  test. 

74 


ENGINE  No.  11 


Head  End 


-60 


40 


20 


-  O 


ENGINE    No.   12, 

Simple  Condensing  Engine. 

Kind  of  engine Four  valve  (Corliss) 

Number  of  cylinders 1 

Diameter  of  cylinder 24i           in. 

Diameter  of  piston  rod 3j           in. 

Stroke  of  piston *......  4              ft. 

Clearance .~  .....  3               % 

H.  P.  constant  for  one  Ib.  m.  e.  p.  one  revolution  per  mm.  .112  H.P. 

Inside  diameter  of  steam  pipe    ...;......  6             in. 

Inside  diameter  of  exhaust  pipe      .     .     .     .     .     .     .     .  7             in. 

Condition  of  valves  and  piston  regarding  leakage  .     .     .      Considerable  leakage 

Data  and  Results  of  Feed- Water  Test. 

Character  of  s'eam      .     .     .     .     ...     .     .     .     .     .     .     .  Ordinary 

Duration 5.07      hrs. 

Weight  of  feed-water  consumed     .     .     .     .     .     ...     ;     .  30,920           Ibs. 

Feed-water  consumed  per  hour      ...     .     .     .     ....  6,099           Ibs. 

Pressure  in  steam  pipe  above  atmosphere    .     .     ...     *.    .  '  .  70.2        Ibs. 

Vacuum  in  condenser       ...... '    ". 21            in. 

Mean  effective  pressure    .     .     .     ...-.-.,.     .  '.     .    '.     .     .     .  33.06     Ibs. 

Revolutions  per  minute 70.2 

Indicated  horse-power .  258.2  I. H.P. 

Feed-water  consumed  per  I.  H.  P.  per  hour     .......  23.62     Ibs. 


Measurements  based  on  Sample  Diagrams. 

Initial  pressure  above  atmosphere ,     .     .     .     63.6      Ibs. 

Cut-off  pressure  above  zero      .     »,    .     .     .;;.     .     .     .     .     .     .     .     56.1      Ibs. 

Release  pressure  above  zero .'....    ",     .    '•„  :  .     17.8      Ibs- 

Mean  effective  pressure  .     .  '  .     ....     .   >     .     .     .     .     «...    .     .     33.31    Ibs. 

Back  pressure  at  mid  stroke,  below  atmosphere  ...     .     .     .     .       8.5      Ibs. 

Proportion  of  stroke  completed  at  cut-off 29 

Steam  accounted  for  at  cut-off 16.99    Ibs. 

Steam  accounted  for  at  release 17.75    Ibs. 

Proportion  accounted  for  at  cut-off .         .719 

Proportion  accounted  for  at  release 751 

Engine  No.  12  exhausts  into  a  jet  condenser  having  a 
direct  connected  air-pump.  The  joints  about  the  air-pump  were 
out  of  repair,  and  the  condenser  was  rendered  somewhat  ineffi- 
cient. Steam  is  supplied  from  vertical  boilers,  which  do  not 
superheat,  but  which  appeared  to  furnish  steam  in  a  commer- 

76 


ENGINE   No.   12. 


77 


cially  dry  condition.  One  of  the  steam  valves  leaked,  but  the 
remaining  valves  were  practically  tight.  The  piston  leaked 
badly.  The  load  consisted  of  cotton  machinery. 

Leakage  and  the  poor  vacuum  are  evidently  accountable  for 
the  comparatively  low  result  obtained  here. 


ENGINE  No.  12 


Head  End 


Crank  End 


~7 


-60 
-40 
-20 

0 

- 10 

-60 
-40 
-20 

-  0 
-10 


ENGINE   No.    13. 

Simple  Non-Condensing  Engine. 

Kind  of  engine Single  valve 

Number  of  cylinders 1 

Diameter  of  cylinder 14.5            in. 

Diameter  of  piston  rod 21              in. 

Stroke  of  piston 13               in. 

Clearance      ...........     ^ 10                 % 

H.  P.  constant  for  one  Ib.  in.  e.  p.  one  revolution  per  min.     .     .  .0108  H.P. 

Inside  diameter  of  steam  pipe .     .     .     .     .     .  4               in. 

Inside  diameter  of  exhaust  pipe 6               in. 

Condition  of  valves  and  piston  regarding  leakage     .     .        Considerable  leakage 

Data  and  Results  of  Feed-Water  Test. 

Character  of  steam Ordinary 

Duration   ....     .    .  .^    .  - .,  .     .  ..--.,  2.5           hr. 

Weight  of  feed-water  consumed     .     .     .     .     .-.'-:.     .     .     .  -  .  4,350             Ibs. 

Feed-water  consumed  per  hour .     .     .     .     .     ...     .     .     .  1,740             Ibs. 

Pressure  in  steain  pipe  above  atmosphere 102.5         Ibs. 

Mean  effective  pressure     .     ..'•'..     .    ">/'',     ...     .....  20.07       Ibs. 

Revolutions  per  minute     .     .     .     .     .     .'-.-    .     .     .     .     .     .  246 

Indicated  horse-power .     .     .     .     .     .     .     .     ..-,.,.     .  53.26  I.H.P. 

Feed-water  consumed  per  I.  H.  P.  per  hour      .     .     .     .     .     .  32.67        Ibs. 

Measurements  based  on  Sample  Diagrams. 

Initial  pressure  above  atmosphere       ...........  98.1       Ibs. 

Cut-off  pressure  above  zero       .     ...     .     .......     .  97.0       Ibs. 

Release  pressure  above  zero     .     .     .     :     .     .     .     .     .     .-   .     .  40.8       Ibs. 

Mean  effective  pressure .    ,. 20.07     Ibs. 

Back  pressure  at  mid  stroke  above  atmosphere    .     .     .     .     .     .  -j-2.6      Ibs. 

Proportion  of  stroke  completed  at  cut-off .119 

Steam  accounted  for  at  cut-off .     .   ..     .     ;";--..    .     .     .     .     .  ;  ,:  17.72    Ibs. 

Steam  accounted  for  at  release       ....     .     ."  ".    >-..   -.     ..  22.59    Ibs. 

Proportion  accounted  for  at  cut-off    .     .     .     .    ..,?.,v ;.  _.  _  .     .  .539 

Proportion  accounted  for  at  release _;__i...-     •  -591 

Engine  No.  13  is  of  the  high-speed  class,  with  a  shaft 
governor.  The  valve  is  of  the  piston  type,  unpacked.  Steam 
is  supplied  from  a  water-tube  boiler,  and  is  presumed  to 
be  in  a  commercially  dry  condition.  The  piston  was  fairly 
tight.  The  valve  at  one  end  was  fairly  tight,  but  at  the  other 
end  it  leaked  badly.  The  load  consisted  of  a  dynamo  furnish- 
ing current  for  electric  lighting. 

The  leaking  of  the  piston  valve  is  evidently  responsible  in 
some  degree  for  the  comparatively  poor  showing  on  this  engine. 

78 


ENGINE  No.  13 


Head  End 


Crank  End 


-100 

-  80 
-60 
-40 
-20 

-  0 
r-100 

-  80 
-60 
—  40 
-20 

-  0 


ENGINE   No.  14. 

Simple  Non- Condensing  Engine. 

Kind  of  engine       ...          . Single  valve 

Number  of  cylinders  .  .1 

Diameter  of  cylinder 8.5  in. 

Diameter  of  piston  rod   .     .     .  If  in. 

Stroke  of  piston     ........  .......      10  in. 

Clearance     .........    v     8  % 

H.  P.  constant  for  1  Ib.  m.  e.  p.  one  revolution  per  min.     .     .          .0028  H.P. 
Inside  diameter  of  steam  pipe       ...........        2£  in. 

Inside  diameter  of  exhaust  pipe 85  in. 

Condition  of  valves  and  piston  regarding  leakage     .     .        Considerable  leakage 

Data  and  Results  of  Feed-  Water  Test. 

Character  of  steam Ordinary 

Duration .  2£          hrs. 

Weight  of  feed-water  consumed     .     .     .     .     .     .'    .     .  ;"\     .  2,357             Ibs. 

Feed- water  consumed  per  hour      .     .     .     .' 942.8          Ibs. 

Pressure  in  steam  pipe  above  atmosphere    '.     .,".:.;.     .     .  105.8          Ibs. 

Mean  effective  pressure    .     .     ...     ...     .     -     .     .     .  30.58        Ibs. 

Eevolutions  per  minute    .   ,.     .-  ....     .     .     .     .     .     .  315 

Indicated  horse-power      .     .     .     ...     .     .     .     .     .     .     .  27.35  I. H.P. 

Feed-water  consumed  per  I.  H.  P.  per  hour     .     » ^  •.     .     .     .  34.44        Ibs. 

Measurements  based  on  Sample  Diagrams. 

Initial  pressure  above  atmosphere ,  99.6      Ibs. 

Cut-off  pressure  above  zero      .     .     .     .     .     ....    f. "   .     .     .  92.5      Ibs. 

Release  pressure  above  zero     .     .     .....     .     .     .     .     .     .     .  34.1      Ibs. 

Mean  effective  pressure 30.58    Ibs. 

Back  pressure  at  mid  stroke  above  atmosphere    .     .     .     .     .     .     .  1.7      Ibs. 

Proportion  of  stroke  completed  at  cut-off    .     .     .     .     .     .     ...  .194 

Steam  accounted  for  at  cut-off  •    .     .     .     .     .     .     .     ...     ...  17.92    Ibs. 

Steam  accounted  for  at  release .     /    .  21.17    Ibs. 

Proportion  accounted  for  at  cut-off  .     ..'.-.     .     ...     .     .  .52 

Proportion  accounted  for  at  release       .     i     .     .     .".-...,.  .615 

Engine  No.  14  is  of  the  high-speed  class,  controlled  by  a 
shaft  governor.  It  is  provided  with  a  piston  valve  which  is 
unpacked.  Steam  is  supplied  from  a  water-tube  boiler,  proba- 
bly in  a  commercially  dry  condition.  The  piston  was  fairly 
tight.  The  valve  leaked  badly.  The  load  consisted  of  a  dy- 
namo furnishing  current  for  electric  lighting. 

The  boiler  plant  in  this  case  is  the  same  as  that  of  Engine 
No.  13. 

The  inferior  economy  exhibited  here  can  be  attributed  in  the 
main  to  leakage. 

80 


ENGINE  No.  14 


Head  End 


ENGINE    No.   15. 

Simple  Condensing  Engine. 

Kind  of  engine Four  valve  (Corliss) 

Number  of  cylinders 2 

Diameter  of  each  cylinder 23            in. 

Diameter  of  each  piston  rod 31           in. 

Stroke  of  each  piston 5             ft. 

Clearance 3               % 

H.  P.  constant  for  1  Ib.  m.  e.  p.  one  revolution  per  min.  .249  H.P. 

Inside  diameter  of  steam  pipe 6            in. 

Inside  diameter  of  exhaust  pipe    .........  10             in. 

Condition  of  valves  and  pistons  regarding  leakage   .     .     .  Fairly  tight 

Data  and  Results  of  Feed- Water  Test. 

Character  of  steam .     .     .     .     .     1     .     ;  Superheated  59° 

Duration 5.63       hrs. 

Weight  of  feed -water  consumed 74,247            Ibs. 

Feed-water  consumed  per  hour 13,187            Ibs. 

Pressure  in  steam  pipe  above  atmosphere 77.6         Ibs. 

Vacuum  in  condenser 27.9           in. 

Mean  effective  pressure 40.49       Ibs. 

Revolutions  per  minute 61 

Indicated  horse-power 615.1    I.H.P. 

Feed-water  consumed  per  I.  H.  P.  per  hour 21.44       Ibs. 

Measurements  Based  on  Sample  Diagrams. 


CONDENSING 
CYLINDER. 


NON- 
CONDENSING 
CYLINDER. 


Initial  pressure  above  atmosphere     .     .     .     Ibs. 

Cut-off  pressure  above  zero Ibs. 

Release  pressure  above  zero Ibs. 

Mean  effective  pressure Ibs. 

Back  pressure  at  mid  stroke,  above  or  be- 
low atmosphere Ibs. 

Proportion  of  stroke  completed  at  cut-off  . 
Steam  accounted  for  at  cut-off      ....     Ibs. 
Steam  accounted  for  at  release     ....     Ibs. 
Proportion  accounted  for  at  cut-off 
Proportion  accounted  for  at  release  .     .     . 


76.7 
80.4 
20.3 
45.33 

11.9 

.264 
16.62 
15.93 


.895 

.874 


73.2 
80.1 
23.6 
36.05 

+  2.6 

.298 
22.41 
22.29 


Engine  No.  15  has  a  pair  of  cylinders  provided  with  a  jet- 
condenser  and  direct  connected  air-pump.  The  exhaust  piping 
is  arranged  so  as  to  run  one  cylinder  condensing  and  the  other 

82 


ENGINE  No. 


non-condensing,  as  was  done  on  the  test.  Steam  is  supplied 
from  vertical  superheating  boilers.  A  small  quantity  of  steam 
was  drawn  from  the  boilers  and  used  for  other  purposes  than 
running  the  engine ;  but  the  quantity  is  insignificant,  and  no 
allowance  is  made  for  it.  The  steam  valves  and  pistons  of 
both  cylinders  were  practically  tight.  There  was  a  slight 
amount  of  leakage  in  all  the  exhaust  valves.  The  engine  was 
employed  in  driving  a  cotton-mill. 

A  test  was  made  on  this  engine  to  determine  the  amount  of 
power  used  by  the  air-pump,  which  had  a  vertical  plunger  22 
in.  diameter  and  12-in.  stroke.  The  connecting-rod  on  the 
condensing  side  was  disconnected,  and  cards  were  taken  from 
the  other  cylinder  first  with  air-pump  in  operation  and  then 
with  air-pump  stopped.  The  load  driven  in  both  cases  was 
the  shafting  of  the  mill.  The  difference  in  the  two  results 
was  10.8  horse-power,  or  1.8%  of  the  working  power  of  the 
engine. 

Sample  indicator  diagrams  from  the  pump  cylinder  are  ap- 
pended, the  first  taken  under  the  working  conditions,  and  the 
second  obtained  on  the  power  test. 

ENGINE  No.  15  AIR  PUMP 


Working  Conditions 


—20 

—  10 
-  O 

—  10 


Power  Test 


—  10 

—  0 

—  10 


ENGINE  No.  15 


R,H.  Cyl.  Head  End 


-60 


-40 


-20 


R.H.  Cyl.  Crank  End 


-  0 

-10 


—60 


—40 


—20 


ENGINE    No.   16. 


Simple  Non-Condensing  Engine. 

Kind  of  engine Single  valve 

Number  of  cylinders 2 

Diameter  of  each  cylinder 9.5             in. 

Diameter  of  each  indicator  rod 375          in. 

Stroke  of  each  piston 9                in. 

Clearance 14.1                % 

H.  P.  constant  for  1  Ib.  m.  e.  p.  one  revolution  per  inin.     .     .  .00322  H.P. 

Inside  diameter  of  steam  pipe 3£               in. 

Inside  diameter  of  exhaust  pipe 3£               in. 

Condition  of  valves  and  pistons  regarding  leakage Some  leakage 

Data  and  Results  of  Feed  -  Water  Tests. 


LETTER  BY  WHICH  TESTS  ABE  DESIGNATED 

A. 

B. 

C. 

Character  of  steam    

Ordinary 

Ordinary 

Ordinary 

Duration      hrs. 

2.908 

2.983 

3.067 

Weight  of  feed-water  consumed  .     Ibs. 

4,248.3 

3,451.9 

2,854.76 

Feed-water  consumed  per  hour   .     Ibs. 

1,460.9 

1,157.2 

930.8 

Pressure   in   steam    pipe    above 

atmosphere     Ibs. 

91  7 

92.5 

92.1 

Mean  effective  pressure       .     .     .     Ibs. 

39.49 

30.76 

22.33 

Revolutions  per  minute       ... 

352.2 

353.9 

356.7 

Indicated  horse-power   .     .     ,     .I.H.P. 

44.81 

35.08 

25.66 

Feed-water  consumed  per  I.  H.  P. 

per  hour    Ibs. 

32.6 

32.99 

36.27 

Measurements  based  on  Sample  Diagrams. 


LETTER  BY  WHICH  TESTS  ARE  DESIGNATED 

A. 

B. 

C. 

Initial  pressure  above  atmosphere     Ibs. 
Cut-off  pressure  above  zero     .     .     Ibs. 
Release  pressure  above  zero     .     .     Ibs. 
Mean  effective  pressure       .     .     .     Ibs. 
Back  pressure  at  mid  stroke  above 
atmosphere  Ibs. 
Proportion    of  stroke  completed 
at  cut-off 

84.7 
79.1 
38.3 
39.57 

+  2.1 
.353 

85.3 
77.1 
33.8 
30.55 

+2.8 
.278 

82.7 
76.4 
30.6 
22.29 

+4. 
.206 

Steam  accounted  for  at  cut-off     .     Ibs. 
Steam  accounted  for  at  release    .     Ibs. 
Proportion  accounted  for  at  cut- 
off     
Proportion   accounted  for  at  re-  . 
lease     .     .     .     .     .     .  .  -.  ""*". 

22.92 
23.27 

.703 
.714 

21.51 

22.89 

/  .652 
.694 

19.92 

24.07 

.549 
.664 

Engine  No.  16  has  a  pair  of  vertical,  single-acting  cylinders 
with  working  parts  inclosed  in  a  chamber  partly  filled  with  oil. 
The  valve,  which  is  common  to  both  cylinders,  is  of  the  piston 

85 


86 


ENGINE    TESTS. 


type  with  ring  packing.  Steam  is  supplied  by  a  vertical  boiler 
having  only  a  small  amount  of  steam-heating  surface.  At  a 
point  near  the  throttle  valve  a  calorimeter  test  showed  the 
presence  of  3%  of  moisture,  no  allowance  for  which  is  made 
in  the  record  of  results.  The  pistons  were  practically  tight. 
The  valve  leaked  a  small  amount.  The  load  consisted  of  a 
Prony  brake  applied  to  the  fly-wheel. 

The  tests  were  three  in  number,  made  with  different  loads. 

In  these  tests  it  appears  that  the  economy  of  the  engine  was 
not  materially  affected  by  reducing  the  load  from  44.81  H.  P. 
to  35.08  H.  P.  A  further  reduction,  however,  increased  the 
consumption. 

In  connection  with  this  series  of  tests,  experiments  were 
made  on  the  effect  of  a  reduction  of  speed.  It  was  found  that 
with  a  speed  of  201.1  revolutions  per  minute,  the  steam  con- 
sumption per  horse  power  per  hour  was  increased  10  per  cent. 


ENGINE  No.  IGa 


R.H.Cyl. 


ENGINE  No.  16b 


R.H.Cyl. 


80- 
60- 
40- 
20- 

0- 
80 
GO 
40 
20 

0- 


ENGINE  No.  16c 


R.H.Cyl. 


L.H.Cyl. 


ENGINE    No.   17, 


Simple  Condensing  Engine. 

Kind  of  engine 

Number  of  cylinders 

Diameter  of  each  cylinder 

Diameter  of  piston-rod 

Stroke  of  piston 

Clearance 

H.P.  Constant  for  one  Ib.  m.e.p.  one  rev.  per  min.     . 
Condition  of  valves  and  pistons  regarding  leakage  . 


Four  valve 

1 
18          ins. 

2|        ins. 
30          ins. 

5  % 

.031  H.P. 
Fairly  tight 


Data  and  Eesults  of  Feed -Water  Tests. 


CONDITIONS  REGARDING  USE  OF 
TEST. 

CONDENSER. 

CONDENSING. 
A. 

NON- 
CONDENSING. 
B. 

Character  of  steam  .... 
Duration 

.      .     hrs. 

Ordinary 
4  1 

Ordinary 
4 

Weight  of  feed-water  consumed 
Feed-water  consumed  per  hour 
Pressure   in  steam  pipe  above 
phere 

.      .     .     Ibs. 
.     .     .     Ibs. 
atmos- 
Ibs 

19.298. 
4,707. 

67 

24,201. 
6,050.2 

67  6 

Vacuum  in  condenser 

ins 

25  5 

Mean  effective  pressure 

Ibs. 

33  75 

33  34 

Kev   per  min 

165  6 

164  4 

Indicated  horse-power  . 

.     .      I.H.P. 

213.2 

209  1 

Feed-water  consumed  per  I.  H.P 

per  hour  Ibs. 

22.08 

28.93 

Measurements  Based  on  Sample  Diagrams. 


CONDITIONS  REGARDING  USE  OF  CONDENSER. 
TEST. 

CONDENSING 
A. 

NON- 
CONDENSING 
B. 

Cut-off  pressure  above  zero                         Ibs. 

62.1 

64.5 

Release  pressure  above  zero                       Ibs. 

18.0 

28.2 

Mean  effective  pressure                               Ibs. 

33.99 

33.75 

Back  pressure  at  mid  stroke,  above  or 

below  atmosphere                                 Ibs. 

—10.3 

+1.5 

Proportion  of  stroke  completed  at  cut-off 

.264 

.385 

Steam  accounted  for  at  cut-off   .     .     .     Ibs. 

17.11 

23.75 

Steam  accounted  for  at  release  .     .     .     Ibs. 

17.5 

23.54 

Proportion     accounted    for    at    cut-off 

(average  of  two  ends)  

.77 

.82 

Proportion  accounted  for  at  release      .     Ibs. 

.79 

.81 

Engine  No.  17  has  balanced  slide  valves.  The  condenser  is 
of  the  siphon  pattern  supplied  with  injection  water  under  a 
natural  head.  Steam  is  taken  from  return  tubular  boilers,  and 
it  is  presumed  to  be  commercially  dry.  The  valves  were  prac- 

88 


ENGINE  No.    17. 


89 


tically  tight,  but  the  pistons  showed  a  small  amount  of  leakage. 
The  load  was  cotton  machinery. 

Two  tests  were  made,  one  with  the  condenser  in  operation, 
and  the  other  with  the  engine  exhausting  into  the  atmosphere. 

From  these  figures  it  appears  that  the  use  of  the  condenser 
secured  a  reduction  in  the  weight  of  steam  consumed  amounts 
ing  to  24%.  This  comparison  is  made  under  conditions  of  a 
comparatively  low  boiler  pressure. 


OF    THK 

UNIVERSITY 


ENGINE  No.  17a 


Head  End 


ENGINE  No.  17b 


60- 


40- 


20- 


O-1 


Head  End 


60- 


40 


20- 


Crank  End 


ENGINE  No.   18. 


Simple  Condensing  Engine. 
Kind  of  engine Four  valve  (Corliss) 


...  2 

...  20i   ins. 

...  3     ins. 

...  4       ft. 

...  3.4     % 

.     .     .  .0772 
6     ins. 

Condition  of  valves  and  pistons  regarding  leakage Fairly  tight 

Data  and  Results  of  Feed -Water  Tests,  Engine  No.  18. 


Number  of  cylinders 

Diameter  of  each  cylinder       .          

Diameter  of  each  piston  rod    ......... 

Stroke  of  each  piston          

Clearance 

H.P.  Constant  for  one  Ib.  m.e.p.,  one  rev.  per  minute 
Inside  diameter  of  steam  pipe 


TEST. 
CYLINDERS  IN  USE. 

A. 

ONE. 

B. 
BOTH. 

Character  of  steam   .          

Ordinary 

Ordinary 

Duration          

hrs. 

5.867 

5.844 

Weight  of  feed-water  consumed  .... 
Feed-water  consumed  per  hour  .... 
Pressure  in  steam  pipe  above  atmosphere  . 
Vacuum  in  condenser                        .     .     . 

Ibs. 
Ibs. 
Ibs. 
ins. 

24,310. 
4,143.5 

84.5 

26.4 

25,045. 
4,285.6 
59. 
25.9 

Mean  effective  pressure      
Revolutions  per  minute 

Ibs. 

43.2 
61.16 

21.84 
61.8 

Indicated  horse-power  I 
Feed-water  consumed  per  I.  H.P.  per  hour 

H.P. 

Ibs. 

204.02 
20.31 

208.45 
20.56 

Measurements  based  on  Sample  Diagrams. 


TEST. 
CYLINDERS  IN  USE. 

A. 
ONE. 

B. 
BOTH. 

Initial  pressure  above  atmosphere      .     .     . 

Ibs. 

82.7 

56.8 

Steam-pipe  pressure  above  atmosphere    . 

Ibs. 

85.3 

60.5 

Cut-off  pressure  above  zero  ...... 

Ibs 

89.3 

64.9 

Release  pressure  above  zero      

Ibs. 

18.0 

8.7 

Mean  effective  pressure    .               ... 

Ibs. 

42.51 

21.72 

Back  pres.  at  mid  stroke  below  atmosphere  . 

Ibs. 

—  11.7 

—11.9 

Proportion  of  stroke  completed  at  cut-off    . 

.188 

.111 

Steam  accounted  for  at  cut-off       .... 

Ibs. 

14.73 

13.73 

Steam  accounted  for  at  release      .... 

Ibs. 

14.8 

14.61 

Proportion  accounted  for  at  cut-off    . 

.725 

.668 

Proportion  accounted  for  at  release   .     .     . 

.729 

.711 

Engine  No.  18  has  a  pair  of  cylinders  with  a  jet  condenser 
operated  by  a  direct  connected  air-pump.  Steam  is  furnished 
by  return  tubular  boilers,  and  calorimeter  tests  showed  that  the 

91 


92  ENGINE    TESTS. 

percentage  of  moisture  varied  from  -J-  to  1  per  cent.  The 
steam  valves  were  fairly  tight.  The  piston  and  exhaust 
valves  of  one  cylinder  were  absolutely  tight.  Those  of  the 
other  cylinder  leaked  a  trifle.  The  load  consisted  of  cotton 
machinery. 

Two  tests  were  made,  one  with  both  cylinders  in  operation 
and  the  other  with  a  single  cylinder,  and  in  both  the  load  was 
practically  the  same.  The  tests  were  made  with  different 
boiler  pressures. 

In  this  case  it  appears  that  the  economy  of  feed-water  con- 
sumption was  practically  the  same  whether  one  cylinder  was 
used  or  the  whole  engine.  As  would  be  expected,  however, 
the  proportion  of  steam  accounted  for  by  the  indicator  was  the 
least  in  the  case  of  the  earlier  expansion. 

In  a  series  of  experiments,  of  which  these  formed  a  part,  a 
test  was  made  to  determine  the  effect  of  increasing  the  boiler 
pressure  20  Ibs.  above  the  normal,  one  cylinder  being  in  use. 
In  one  case  the  pressure  was  85.8  Ibs.,  and  in  the  other  105.7 ; 
and  the  mean  effective  pressure  was,  in  round  numbers,  41  Ibs. 
in  both  cases.  The  cut-off  occurred  at  TVo  of  the  stroke  in 
one,  and  y1^  of  the  stroke  in  the  other.  The  steam  consump- 
tion with  the  high  pressure  was  19.5  Ibs.  per  I.  H.  P.  per  hour, 
and  with  the  low  pressure  19.2.  In  other  words,  there  was  a 
trifling  loss  due  to  the  increase  of  pressure.  This  engine  was 
not  absolutely  tight,  and  doubtless  leakage  affected  the  results, 
so  that  the  advantage  of  the  increase  of  pressure  was  to  some 
extent  counteracted. 

On  the  last  mentioned  test  the  steam  accounted  for  was  .67. 


ENGINE  No.  18a 


80-, 
60- 
40- 
20- 
0 


Head  End 


80- 
60- 
40- 
20 

0- 
10- 


Crank  End 


UNIVERSITY 


ENGINE  No.  18b 


R.H.  Cyl.  Head  End 


R.H,  Cyl.  Crank  End 


-60 
-40 
-20 

-  0 
-10 

r-60 
-40 
-20 

—  0 

-10 


60- 
40- 
20- 

0- 
10- 


L.H.  Cyl.  Head  End 


60  -, 
40- 
20- 

0- 
10- 


L.H.  Cyl.  Crank  End 


ENGINE    No.    19. 

Simple  Condensing  Engine. 

Kind  of  engine Single  Valve 

Number  of  cylinders       ...» 1 

Diameter  of  cylinder      .     .     .     .     .     , 18.5           in. 

Diameter  of  piston  rod .     .     .  2i             in. 

Stroke  of  piston ".•'•.•  '•     .     .     .     .    >     .  30.             in. 

Clearance ......  7.5             % 

H.  P.  Constant  for  one  Ib.  in.  e.  p.  one  rev.  per  minute       .     .  .0405  H.P. 

Condition  of  valves  and  pistons  regarding  leakage Some  leakage 

Data  and  Eesults  of  Feed -Water  Test. 

Character  of  steam    .     .     . Ordinary 

Duration .     .     .     .     .  5.011     hrs. 

Weight  of  feed-water  consumed -   ...     .     .     .  27,838.1        Ibs. 

Feed-water  consumed  per  hour    .     .     .     ...     .     ,    ..    V  5,555.4        Ibs. 

Pressure  in  steam  pipe  above  atmosphere '  -.     .  74.5       Ibs. 

Vacuum  in  condenser .  24.8       ins. 

Mean  effective  pressure .     .     .     .     .  39.05     Ibs. 

Revolutions  per  minute      ....     .     .     .     .     .     .     .     .  129.33 

Indicated  horse-power  .     .     ...     ...     .     .     .     .     .  204.59     H.P. 

Feed-water  consumed  per  I.  H.  P.  per  hour 27.15     Ibs. 

Measurements  based  on  Sample  Diagrams. 

Initial  pressure  above  atmosphere 69.3  Ibs. 

Steam-pipe  pressure 73.2  Ibs. 

Cut-off  pressure  above  zero     .     .     .     .     .     .     .....     66.8  Ibs. 

Release  pressure  above  zero 29.0  Ibs. 

Mean  effective  pressure .     .     38.1  Ibs. 

Back  pressure  at  mid  stroke,  below  atmosphere      ....  — 8.9  Ibs. 

Proportion  of  stroke  complete  at  cut-off    .......         .303 

Steam  accounted  for  at  cut-off     .     .     .     .     .     .     .     .     .     .     19.17  Ibs. 

Steam  accounted  for  at  release .     18.97  Ibs. 

Proportion  accounted  for  at  cut-off .........         .  706 

Proportion  accounted  for  at  release     :.:    . 699 

Engine  No.  19  has  a  single  unpacked  piston  valve,  controlled 
by  a  shaft  governor.  The  engine  is  provided  with  a  jet  con- 
denser operated  by  an  independent  air-pump,  driven  by  steam. 
The  steam  used  by  the  condenser  was  determined  separately, 
and  allowance  made  for  it  in  the  record.  Steam  is  supplied  by 
horizontal  return  tubular  boilers,  and  it  is  presumed  that  it  was 
in  a  commercially  dry  condition.  The  piston  of  the  engine 
was  tight,  but  the  valve  placed  at  the  middle  of  its  throw 
showed  considerable  leakage.  The  load  was  cotton  machinery. 

95 


ENGINE  No.  19 


Head  End 


60 
-40 
-20 

-  0 
-10 

-60 
-40 
-20 

0 

-  10 


ENGINE    No.  2O. 


Simple  Condensing. 

Kind  of  engine 

Number  of  cylinders 

Diameter  of  each  cylinder  .     . 

Diameter  of  each  piston  rod 

Stroke  of  each  piston 

Clearance 

H.P.  constant  for  one  Ib.  in.e.p.  one  rev.  per  minute  . 

Inside  diameter  of  steam  pipe 

Inside  diameter  of  exhaust  pipe 


2 

28 
4 
5 
3 


Four  valve 

ins. 

ins. 
ft. 


Condition  of  valves  and  pistons  regarding  leakage  . 

Data  and  Results  of  Feed- Water  Tests. 


.3694  H.P. 

9  ins. 

10  ins. 

Some  leakage 


TEST. 
CONDITIONS  REGARDING  USE  OF  CONDENSER. 

A. 

CONDENSING. 

B. 
NON- 
CONDENSING. 

Character  of  steam     .     .     .     .     .     .     .     . 

Ordinary. 

Ordinary 

Duration       .           

hrs. 

10.08 

9.83 

Weight  of  feed-water  consumed  .... 

Ibs. 

102,947. 

133,925. 

Feed-water  consumed  per  hour    .... 

Ibs. 

10,213. 

13,620. 

Pressure  in  steam  pipe  above  atmosphere   . 

Ibs. 

68.1 

65.1 

Vacuum  in  condenser     

ins. 

23. 

Mean  effective  pressure  

Ibs. 

23.12 

23.81 

Revolutions  per  minute  

52. 

50  5 

Indicated  horse-power    I 

H.P. 

444. 

451.6 

Feed-water  consumed  per  I.  H.P.  per  hour 

Ibs. 

23. 

30.16 

Measurements  based  on  Sample  Diagrams. 


TEST. 
CONDITIONS  REGARDING  USE  OF  CONDENSER 

. 

A. 

CONDENSING 

B. 
NON- 
CONDENSING. 

Initial  pressure  above  atmosphere 
Steam-pipe  pressure  
Cut-off  pressure  above  zero     
Release  pressure  above  zero    
Mean  effective  pressure 

Ibs. 
Ibs. 
Ibs. 
Ibs. 
Ibs 

63.6 
68.1 
71.2 
9.5 
23  25 

62.5 
65.7 
70.1 
16.8 
23  97 

Back  pressure  at  mid  stroke,  above  or  be- 
low atmosphere  . 

Ibs 

11  1 

-1-1  5 

Proportion  of  stroke  completed  at  cut-off  . 
Steam  accounted  for  at  cut-off     .... 
Steam  accounted  for  at  release    .... 
Proportion  accounted  for  at  cut-off 
Proportion  accounted  for  at  release.     .     . 

Ibs. 
Ibs. 

.119 
14.13 
14.37 
.615 

.625 

.222 

21.8 
23.17 

.722 
.766 

Engine  No.  20  has  a  pair  of  cylinders  with  gridiron  unbal- 
anced slide  valves.      It  is  fitted  with  a  jet  condenser,  operated 

97 


98  ENGINE    TESTS. 

by  an  independent  air-pump  driven  by  steam.  The  engine  \vas 
supplied  from  horizontal  return  tubular  boilers,  and  the  steam 
on  subsequent  occasions  was  found  to  contain  1.2  °}0  of  moisture. 
In  the  matter  of  leakage,  the  engine  was  in  fair  condition, 
though  every  valve,  and  the  pistons  as  well,  showed  a  small 
amount  of  leakage.  The  load  was  made  up  largely  of  rubber 
grinding  machinery. 

Two  tests  were  made,  one  with  the  condenser  in  operation, 
and  the  other  with  the  engine  exhausting  into  the  atmosphere, 
the  condenser  being  stopped.  Independent  tests  were  made, 
showing  the  quantity  of  steam  used  by  the  air-pump  ;  and 
allowance  has  been  made  for  it.  Besides  the  engine,  the  boiler 
supplied  the  feed-pump  and  a  tank-pump,  The  steam  thus 
used  has  not  been  allowed  for. 

The  air-pump,  which  had  a  single  steam  cylinder  16"  in  diam- 
eter and  24"  stroke,  when  making  56.3  single  strokes  per 
minute,  was  found  to  use  1682  Ibs.  of  steam  per  hour.  The 
power  developed  amounted  to  12.8  H.  P.  ;  consequently  the 
air-pump  consumed  131.7  Ibs.  of  steam  per  I.  H.  P.  per  hour. 
On  the  condensing  test  the  air-pump  used  over  13  per  cent  of 
the  entire  quantity  consumed  by  the  engine. 

The  quantity  of  steam  used  by  the  engine  and  air-pump 
working  condensing  was  about  12  °/0  less  than  that  used  when 
the  engine  was  running  non-condensing,  and  the  quantity  used 
by  the  engine  alone  about  24  °fc  less. 

In  explanation  of  the  comparatively  low  proportion  of  feed- 
water  accounted  for  on  the  condensing  test,  it  is  probable  that 
allowance  made  for  steam  used  by  the  condenser  was  less  than 
the  actual  quantity,  owing  to  the  fact  that  ordinarily  the 
cylinder  drips  were  kept  partially  open.  On  the  condenser 
test,  these  were  closed.  Probably  the  actual  consumption  of 
feed-water  was  somewhat  below  the  23  Ibs.  given  in  the  table, 
and  the  actual  proportions  referred  to  were  somewhat  higher. 
It  should  also  be  noted  that  the  portion  unaccounted  for  in- 
cludes the  steam  used  by  the  boiler-feed  and  tank-pump  on  both 
tests,  probably  2  or  3  %  of  the  whole. 


ENGINE  No.  2Oa 


60- 
40- 
20- 

0- 
10- 

60- 
40- 
20- 

0- 
10- 


L,H.Cyl.  Head  End 


-60 
-40 
-20 

-  0 
-10 

-60 
-40 
-20 

-  0 
-10 


ENGINE  No.  2Ob 


60- 


40 


20- 


RH.Cyl.  Head  End 


60- 


40- 


20 


0-1 


RH.Cyl.  Crank  End 


—  60 


L.H.Cyl.  Head  End 


-40 


20 


L-  0 


-60 


L.H.Cyl.  Crank  End 


-40 


-20 


L  0 


ENGINE    No.  21. 

Simple  Non- Condensing  Engine. 

Kind  of  engine    ......                     ......  Four  valve 

Number  of  cylinders    .....               .,.,...  1 

Diameter  of  cylinder .     .  "  ...    .  11$           ins. 

Diameter  of  piston  rod     .....                 .....  II           ins. 

Stroke  of  piston  .     ....     ..:.'.......'.  20             ins. 

Clearance  .-....' ...     .     .     .     '...    .  10                 % 

H.  P.  constant  for  one  Ib.  m.  e.  p.  one  revolution  per  min.  .0104  H.P. 

Inside  diameter  of  steam  pipe    ....../,..  4              in. 

Condition  of  valves  and  piston  regarding  leakage  .     .     .      Considerable  leakage 

Data  and  Results  of  Feed-Water  Test. 

Character  of  steam      .     .     ,     .     .     .     .     ....     .     .     .  Superheated  4° 

Duration  .     . 8          hrs. 

Weight  of  feed-water  consumed 10,341           Ibs. 

Feed-water  consumed  per  hour ,     .     .     .     .  1,292           Ibs. 

Pressure  in  steam  pipe  above  atmosphere 64.5       Ibs. 

Mean  effective  pressure 15.7       Ibs. 

Revolutions  per  minute 198.3 

Indicated  horse-power ......  32.26I.H.P. 

Feed-water  consumed  per  I.  H.  P.  per  hour 40.04      Ibs. 

Measurements  based  on  Sample  Diagrams. 

Initial  pressure  above  atmosphere 63.1      Ibs. 

Corresponding  steam-pipe  pressure 67         Ibs. 

Cut-off  pressure  above  zero 60.4      Ibs. 

Release  pressure  above  zero 22.4      Ibs. 

Mean  effective  pressure 15.4      Ibs. 

Back  pressure  at  mid  stroke,  above  atmosphere .  2         Ibs. 

Proportion  of  stroke  completed  at  cut-off  .     .     .     «     .••""'.     .     .     .  .238 

Steam  accounted  for  at  cut-off 24.85    Ibs. 

Steam  accounted  for  at  release 25.13    Ibs. 

Proportion  of  feed-water  accounted  for  at  cut-off     .     .     .   , .     .     .  .62 

Proportion  of  feed-water  accounted  for  at  release .627 


Engine  No.  21  has  balanced  slide  valves.  Steam  is  furnished 
from  a  horizontal  return  tubular  boiler  of  special  design,  which 
is  provided  with  a  considerable  amount  of  steam-heating  sur- 
face. The  steam  was  superheated  at  the  boiler  30°,  and  at  a 
point  near  the  engine  4°.  One  of  the  exhaust  valves  and  the 
piston  were  fairly  tight.  The  other  steam  valve  and  the  other 

101 


102 


ENGINE    TESTS. 


exhaust  valve  leaked   very   badly.     The    load   consisted  of  a 
dynamo  furnishing  a  steady  current  for  electric  lighting. 

It  is  evident  that  leakage  of  the  valves  referred  to  had  much 
to  do  with  the  poor  showing. 


ENGINE  No.  21 


80^ 
60- 
40- 
20- 
0- 


HeadEnd 


Crank  End 


r— 80 
-60 
-40 
-20 
—  0 


ENGINE    No.  22. 


Simple  Condensing  Engine. 

Kind  of  engine      . Four  valve 

Number  of  cylinders       ................      1 

Diameter  of  cylinder      ....  ,     .  M&         ins. 

Diameter  of  piston  rod  .... 5  ins. 

Stroke  of  piston 5  ft. 

Clearance    .....      2 

H.P.  constant  for  one  Ib.  m.  e.  p.  one  rev.  per  min 2791H.P. 

Inside  diameter  of  steam  pipe      .     .     .     .......     .     .     .     14          ins. 

Inside  diameter  of  exhaust  pipe 14          ins. 

Condition  of  valves  and  piston  regarding  leakage Some  leakage 


Data  and  Results  of  Feed-  Water  Test. 


Character  of  steam       .... 

Duration  ........ 

Weight  of  feed-water  consumed 
Feed-water  consumed  per  hour 
Pressure  in  steam-pipe     ... 
Vacuum  in  condenser 
Mean  effective  pressure    . 
Revolutions  per  minute    .     ,     . 
Indicated  horse-power      .     . 
Feed-  water  consumed  per  I.  H.  P 


Ordinary 


....  60,879 

Ibs. 

.  ,     .  .  11,343 

Ibs. 

82.3 

Ibs. 

.  .  .  ;.    27.9 

ins. 

.  .    .  .    37.23 

Ibs. 

......    59.9 

613.4  I 

H.P. 

per  hour 


18.49        Ibs. 


Measurements  based  on  Sample  Diagrams. 
Initial  pressure  above  atmosphere     ......... 

Corresponding  steam-pipe  pressure    ........     . 

Cut-off  pressure  above  zero      ....     ....... 

Release  pressure  above  zero     .......     .     .'.'.. 

Mean  effective  pressure  .     .     .     .     .     .     ....,«,.,-, 

Back  pressure  at  mid  stroke  above  or  below  atmosphere  . 
Proportion  of  stroke  completed  at  cut-off  ....... 

Steam  accounted  for  at  cut-off      .......... 

Steam  accounted  for  at  release     .......     . 

Proportion  of  feed-water  accounted  for  at  cut-off     .... 

Proportion  of  feed-water  accounted  for  at  release     .... 


81.9 

84.2 

75.6 

15.5 

37.17 

13.6 

.172 

12.39    Ibs 
13.41    Ibs 

.669 

.725 


Ibs. 
ibs. 
Ibs. 
Ibs. 

Ibs. 
Ibs. 


Engine  No.  22  has  slide  valves  of  the  gridiron  type.  It  is 
provided  with  a  siphon  condenser,  the  injection  water  for  which 
is  furnished  under  natural  head.  Steam  is  supplied  to  the 
engine  from  water  tube  boilers  through  a  16-inch  pipe  331  feet 
in  length.  At  a  point  near  the  engine  it  is  drained  by  means 
of  a  trap,  which  discharges  to  waste.  On  the  test  143  Ibs.  of 
water  were  discharged  per  hour,  and  no  allowance  has  been  made 

103 


104 


ENGINE   TESTS. 


for  this.  At  a  point  between  the  trap  and  the  engine  the  steam 
was  found  by  calorimeter  test  to  contain  2^  per  cent  of  mois- 
ture. The  exhaust  valves  were  practically  tight.  The  steam 
valves  and  pistons  showed  some  leakage.  The  engine  worked 
in  connection  with  a  water-wheel  driving  cotton  machinery. 

In  examining  the  results  of  this  test,  which  in  view  of  the 
long  distance  which  the  steam  had  to  travel  between  the  boil- 
ers and  the  engine,  shows  excellent  economy,  the  part  which 
the  vacuum  played  cannot  be  overlooked.  This  was  phenomi- 
nally  low,  the  back  pressure  at  the  middle  of  the  stroke  being 
only  about  one  pound  above  a  perfect  vacuum. 


ENGINE  No.  22 


Head  End 


Crank  End 


C 


-80 
-60 
-40 
-20 

-  0 
-10 

QO 

60 

40 

-20 

-  0 

-10 


ENGINE    No.  23. 


I A 


Simple  Non- Condensing  Engine. 

Kind  of  engine .    "._       Single  valve 

Number  of  cylinders ...     .....       1 

Diameter  of  cylinder ,. 

Diameter  of  piston  rod 

Stroke  of  piston '.-.'.-.- 12 

Clearance     

H.  P.  constant  for  1  Ib.  m.  e.  p.  one  revolution  per  min. 

Inside  diameter  of  steam  pipe 

Inside  diameter  of  exhaust  pipe 

Condition  of  valves  and  piston  regarding  leakage     .... 


ins. 
ins. 
ins. 
14  % 

.00301  H.P. 
3  ins. 

3£  ins. 

Fairly  tight 


Data  and  Results  of  Feed -Water  Tests. 


TESTS. 

A. 

B. 

C. 

Character  of  steam    
Duration      hrs. 
Weight  of  feed-water  consumed  .     Ibs. 
Feed-water  consumed  per  hour   .     Ibs. 
Pressure    in   steam    pipe     above 
atmosphere     Ibs. 
Mean  effective  pressure       .     .     .     Ibs. 
Revolutions  per  minute 
Indicated  horse-power   .     .     .      I.H  P 

Ordinary 
3 
2,140 
713.3 

83 
24.53 
303.7 
22.45 

Ordinary 
4 
4,035 

1,008.8 

82.4 
34.86 
307.8 
32  33 

Ordinary 
4 
4,833 
1,208.2 

81.9 
42.99 
304.5 
39  44 

Feed-water  consumed  per  I.  H.  P. 
per  hour    Ibs. 

31.78 

31.2 

30.63 

Measurements  based  on  Sample  Diagrams. 


TESTS. 

A. 

B. 

C. 

Initial  pressure  above  atmosphere    Ibs. 
Corresponding  steam-pipe  pressure    Ibs. 
Cut-off  pressure  above  zero     .     .     Ibs. 
Release  pressure  above  zero     .     .     Ibs. 
Mean  effective  pressure       .     .     .     Ibs. 
Back  pressure  at  mid  stroke  above 
atmosphere  Ibs. 
Proportion    of   stroke  completed 
at  cut-off  

78.8 
83 
76.2 
27.4 
24.61 

.8 
203 

77.3 
82 
75.5 
32.5 
34.79 

.7 
312 

79.5 
81.8 
78.1  ' 
37.3 
43.12 

.7 
378 

Steam  accounted  for  at  cut-off     .     Ibs. 
Steam  accounted  for  at  release    .     Ibs. 
Proportion  of  feed  water  account- 
ed for  at  cut-off     .... 
Proportion  of  feed  water  account- 
ed for  at  release    ... 

20.4 
21.66 

.642 

.681 

22.48 
21.76 

.72 
.698 

23.33 
22.24 

.762 
.726 

Engine  No.  23  has  a  single-slide  valve  which  is  balanced  by 
means  of  a  pressure-plate  riding  on  the  back,  and  the  cut-off  is 

105 


106 


ENGINE    TESTS. 


made  automatic  through  the  action  of  a  shaft  governor.  Steam 
is  supplied  from  a  horizontal  return  tubular  boiler.  A  calorim- 
eter test  showed  that  it  was  practically  dry.  The  piston  was 
fairly  tight.  The  valve  showed  some  leakage.  The  load  con- 
sisted of  a  Sturtevant  Blower.  A  series  of  tests  were  made 
under  conditions  of  different  loads,  but  practically  constant 
boiler  pressure. 

Another  test  in  the  same  series  with  a  load  of  28.44  I.  H.  P., 
which  is  intermediate  between  the  first  and  the  second,  gave  a 
feed-water  consumption  of  31.46  Ibs.  per  I.  H.  P.  per  hour,  and 
the  proportions  of  steam  accounted  for  were  respectively  .685 
and  .694.  In  this  series  of  tests  the  gradual  improvement  in 
the  economy  as  the  load  is  increased  is  a  noticeable  feature,  as 
is  also  the  uniform  increase  in  the  proportion  of  steam  ac- 
counted for  at  the  cut-off.  Another  point  to  be  noticed  is  that 
as  the  cut-off  becomes  later,  the  amount  of  steam  present  at  the 
release  compared  with  that  at  cut-off  is  gradually  reduced.  In 
the  first  experiment  the  steam  at  release  is  the  greater  of  the 
two,  while  in  the  last  it  is  the  smaller. 

80-,     |\  ENGINE  No.  23a 


60- 


40- 


20- 


0- 
80^ 


60- 


40- 


20- 


Head  End 


Crank  End 


ENGINE  No.23b 


40 


20 


Head  End 


0— 


ENGINE    No.  24. 

Simple  Non- Condensing  Engine. 

Kind  of  engine  .     .     .     .     .     ... ,,  Single  valve 

Number  of  cylinders  .........     .^    ...  I 

Diameter  of  cylinder ...',...  14.5        ins. 

Diameter  of  piston  rod    ............  2£          ins. 

Stroke  of  piston      ....     .  .   ..'  .     .     .     , '   •.     .     .     .  13            ins. 

Clearance - .     .     .     .  12                % 

H.  P.  constant  for  1  Ib.  in.  e.  p.  one  revolution  per  min.  .0107  HP. 

Inside  diameter  of  steam  pipe 5            ins. 

Condition  of  valves  and  piston  regarding  leakage     .     .     .  Fairly  tight 

Data  and  Results  of  Feed-  Water  Test 

Character  of  steam Ordinary 

Duration (,  4.45       hrs. 

Weight  of  feed-water  consumed '. " '  .  8,983             Ibs. 

Feed-water  consumed  per  hour 2,018.6         Ibs. 

Pressure  in  steam  pipe  above  atmosphere 80.3          Ibs. 

Mean  effective  pressure 23.22        Ibs. 

Revolutions  per  minute 248.4 

Indicated  horse-power ';  61.7    I.H.P. 

Feed-water  consumed  per  I.  H.  P.  per  hour 32.71        Ibs. 

Measurements  based  on  Sample  Diagrams. 

Initial  pressure  above  atmosphere ...     .  78.4  Ibs. 

Corresponding  steam-pipe  pressure 80.5  Ibs. 

Cut-off  pressure  above  zero       .     ...     .     .     .....••    ...     .  74.1  Ibs. 

Release  pressure  above  zero 29.6  Ibs. 

Mean  effective  pressure •    »     .     .  23.43  Ibs. 

Back  pressure  at  mid  stroke  above  atmosphere 2.6  Ibs. 

Proportion  of  stroke  completed  at  cut-off .211 

Steam  accounted  for  at  cut-off 21.66  Ibs. 

Steam  accounted  for  at  release 23.57  Ibs. 

Proportion  of  feed-water  accounted  for  at  cut-off .662 

Proportion  of  feed-water  accounted  for  at  release .721 

Engine  No.  24  is  of  the  high-speed  type,  with  an  unpacked 
piston  valve  controlled  by  a  shaft  governor.  Steam  was  sup- 
plied from  a  horizontal  return  tubular  boiler  in  what  was 
believed  to  be  a  commercially  dry  state.  The  valve  was  new, 
well  fitted,  and  fairly  tight.  The  piston  was  also  fairly  tight. 
The  load  consisted  mainly  of  machinery  for  the  manufacture  of 
woolen  yarns. 

108 


ENGINE  No.  24 


Head  End 


1—80 


—  60 


-40 


-  20 


L-    0 


Crank  End 


r-  80 


-  60 


-40 


-20 


L-     0 


ENGINE    No.  25. 


Simple  Condensing  Engine. 

Kind  of  engine *.     .          Four  valve  (Corliss) 

Number  of  cylinders  .     .     .     .     .     .     .     .  •  -.  .  .     .     ...     .       2 

Diameter  of  each  cylinder   .     .     .     .     .     .     .     ,     .     .     ,     ;     .26  ins. 

Diameter  of  each  piston  rod     .     .     .     .     .     .  ~  .     .     .     .     .     .       3|  ins. 

Stroke  of  each  piston .     .     .     .     . .     '.-.-.        5  ft. 

Clearance •...-...-.     .     .   ~.  3  % 

H.  P.  constant  for  one  Ib.  m.  e.  p.  one  revolution  per  minute 

each  cylinder .16      H.P. 

Inside  diameter  of  steam  pipe 8  ins. 

Inside  diameter  of  exhaust  pipe 10  ins. 

Condition  of  valves  and  pistons  regarding  leakage Some  leakage 

Data  and  Results  of  Feed  Water  Test. 

Character  of  steam Ordinary 

Duration '..     .     .     .  1.75       hrs. 

AVeight  of  feed-water  consumed 24,416             Ibs. 

Feed-water  consumed  per  hour 13,948             Ibs. 

Pressure  in  steam  pipe  above  atmosphere 82.9         Ibs. 

Vacuum  in  condenser 25.9          ins. 

Mean  effective  pressure 36.29       Ibs. 

Revolutions  per  minute 53.9 

Indicated  horse-power 625.6    I. H.P. 

Feed-water  consumed  per  I.  H.  P.  per  hour 22.29        Ibs. 

Measurements  Based  on  Sample  Diagrams. 


THREE  ENDS 
CONDENSING. 


ONE  END 

NON- 
CONDENSING. 


Initial  pressure  above  atmosphere     .     .     .     Ibs. 

Corresponding  steam-pipe  pressure  .     .     .     Ibs. 

Cut-off  pressure  above  zero Ibs. 

Release  pressure  above  zero Ibs. 

Mean  effective  pressure Ibs. 

Back  pressure  at  mid  stroke,  above  or  be- 
low atmosphere Ibs. 

Proportion  of  stroke  completed  at  cut-off  . 

Steam  accounted  for  at  cut-off      ....     Ibs. 

Steam  accounted  for  at  release     ....     Ibs. 

Proportion  of  feed-water  accounted  for  at 
cut-off,  average  

Proportion  of  feed-water  accounted  for  at 
release,  average.  .  ."  .  .  .  .  . 


79.9 
83.4 
73.2 
19.2 
40.25 

10. 

.245 
15.49 
15.59 


79.7 
83.4 
66.2 
17.6 
23.94 

+  3.5 

.24 
21.17 
22.23 


.737 
.740 


Engine  No.  25  has  a  pair  of  horizontal  cylinders  exhausting 
into  a  jet  condenser  which  is  operated  by  a  direct  connected 

110 


ENGINE   No.   25. 

air-pump.  The  cylinders  were  arranged  for  running  one  end 
of  one  cylinder  non-condensing,  and  it  was  under  these  condi- 
tions that  the  tests  were  made.  Steam  is  furnished  by  cylinder 
boilers,  and  it  is  presumed  that  it  was  in  a  commercially  dry 
condition.  When  the  water  was  carried  at  an  unusually  low 
point,  a  small  portion  of  the  shell  became  steam-heating  sur- 
face, and  the  steam  was  found  to  be  slightly  superheated.  Two 
of  the  steam  valves-  showed  some  leakage.  The  pistons  also 
leaked  a  small  amount.  The  remaining  valves  were  fairly 
tight.  The  load  consisted  of  cotton  machinery. 


ENGINE  No.  25 


RH.Cyl.  Head  End 


r80 


-60 


-40 


20 


ENGINE    No.   26. 


Simple  Non-Condensing  Engine. 

Kind  of  engine Four  valve 

Number  of  cylinders 1 

Diameter  of  cylinder 16j 

Diameter  of  piston  rod 21 

Stroke  of  piston 3 

Clearance 6  % 

H.P.  Constant  for  one  Ib.  m.e.p.  one  rev.  per  rnin 03717  H.P. 

Condition  of  valves  and  piston  regarding  leakage       ....     Leakage  Test  A 

Data  and  Results  of  Feed  -Water  Tests. 


ins. 

ins. 

ft. 


TEST. 

A. 

B. 

Character  of  steam  .     . 
Duration     
Weight  of  feed-water  consumed 
Feed-water  consumed  per  hour 
Pressure   in   steam  pipe  above 
phere 

.    hrs. 
.      .     .     Ibs. 
.     .     .     Ibs. 
atmos- 

Ihs 

Ordinary 
3.117 
7,207. 
2,312.2 

74.2 
25.17 
75.8 
70.9 
32.61 

Ordinary 
3. 
6,221. 
2,073.7 

74. 
24.89 
76.03 
70.6 
29.37 

Mean  effective  pressure     .               .     .     Ibs. 
Revolutions  per  minute      
Indicated  horse-power  I.  H.P. 
Feed-water  consumed  per  I.  H.P.  per  hour,  Ibs. 

Measurements  based  on  Sample  Diagrams. 


TEST. 

A. 

B. 

Initial  pressure  above  atmosphere 

Ibs. 

66.2 

66.5 

Corresponding  steam-pipe  pressure     . 

Ibs. 

74.2 

74. 

Cut-off  pressure  above  zero  

Ibs. 

64.7 

65.5 

Release  pressure  above  zero      

Ibs. 

18.5 

18.3 

Mean  effective  pressure    

Ibs. 

25.17 

24.89 

Back  pres.  at  mid  stroke  above  atmosphere  . 

Ibs. 

1.9 

1.7 

Proportion  of  stroke  completed  at  cut-off    . 

.237 

.223 

Steam  accounted  for  at  cut-off       .... 

Ibs. 

22.55 

21.87 

Steam  accounted  for  at  release       .... 

Ibs. 

24.65 

24.64 

Proportion  of  feed-water  accounted  for  at 

cut-off                         

.692 

.745 

Proportion  of  feed-water  accounted  for  at 

release    

.755 

.839 

Engine  No.  26  has  double  poppet  steam  valves,  and  plain 
slide  exhaust  valves.  Steam  is  drawn  from  horizontal  return 
tubular  boilers.  The  load  was  a  machine  shop.  The  valves 
and  piston  were  practically  tight  on  test  B.  On  test  A  the 

113 


114  ENGINE    TESTS. 

exhaust  valve  leaked  badly,  and  during  the  interval  between 
the  two  it  was  repaired. 

The  effect  of  exhaust  valve  leakage  on  the  economy  of  the 
engine  is  here  clearly  revealed.  The  tighter  engine  used  about 
10%  less  steam.  The  effect  of  the  leakage  upon  the  lines  of 
the  diagrams  is  hardly  noticeable. 


ENGINE  No.  26a 


60 


40- 


20- 


60- 


40- 


20- 


Crank  End 


60- 


ENGINE  No.  26b 


40- 


Heacl  End 


20- 


40 


20- 


Crank  End 


ENGINE    No.  27. 

Simple  Non-Condensing  Engine. 

Kind  of  engine Single  valve 

Number  of  cylinders "   * 1 

Diameter  of  cylinder      .     .     .     .     .     ...     .     .     »     .     .     .     .  121             ins. 

Diameter  of  piston  rod .     .     .     .....  2?            ins. 

Stroke  of  piston 20              ins. 

Clearance ....*....',    V    ...  8                 % 

H.  P.  constant  for  1  Ib.  in.  e.  p.  one  revolution  per  minute      .  . 01219  H. P. 
Condition  of  valves  and  piston  regarding  leakage     .     .        Considerable  leakage 

Data  and  Results  of  Feed-Water  Test. 

Character  of  steam      .     .     .     .     .     .     .     .     .     .     .     .     .'  .  Ordinary 

Duration.     ...     .     .     .     .     .     .     .'  '..     .     .     .     .     .  .'  3.083     hrs. 

Weight  of  feed-water  consumed     .     ...     .     .     .     .     .  .  4,374.5          Ibs. 

Feed-water  consumed  per  hour      .     .     »     ....     ..."  .  1,418.9          Ibs. 

Pressure  in  steam  pipe  above  atmosphere    .     .     .     .     .     .  .  72.2         Ibs. 

Mean  effective  pressure 18.15        Ibs. 

Revolutions  per  minute    .     .     .     .     .     .     .•     .     ...     •  •  172.3 

Indicated  horse-power      . ,     .     .     .     .     .  .  38.1    I.H.P. 

Feed-water  consumed  per  I.  H.  P.  per  hour     .     .     .  . -,     .  .  37.21        Ibs. 

Measurements  based  on  Sample  Diagrams. 

Initial  pressure  above  atmosphere      .     .     .     ...     .     .     .     .     .  68.8      Ibs. 

Corresponding  steam-pipe  pressure   .     .     ......     .     .     .  72.2      Ibs. 

Cut-off  pressure  above  zero      ...     .     '.     .     .     .     ...    .     .           .     .  66.5      Ibs. 

Release  pressure  above  zero 26.4      Ibs. 

Mean  effective  pressure        \  .     ...     ...     *     .  18.15    Ibs. 

Back  pressure  at  mid  stroke  above  atmosphere    .     .     .....     .  3.5      Ibs. 

Proportion  of  stroke  completed  at  cut-off    .     .     .     ......  .219 

Steam  accounted  for  at  cut-off      .'.     .     .     .     .     .     .     .     .     .  .  :.  21.13    Ibs. 

Steam  accounted  for  at  release      .     .     .     ...     .     .     .     !.     .     .  26.74    Ibs. 

Proportion  of  feed-water  accounted  for  at  cut-off     .     .     .     .     .     •  -568 

Proportion  of  feed-water  accounted  for  at  release    .     .     .     ...  .719 

Engine  No.  27  is  of  the  high-speed  class,  with  unpacked 
piston  valve  operated  through  a  shaft  governor.  The  boiler  is 
of  the  horizontal  return  tubular  type.  The  leakage  of  the 
engine  was  confined  mainly  to  the  valve.  The  load  consisted 
of  machine  tools. 

The  engine  being  located  at  a  distance  of  some  75  ft.  from 
the  boiler,  the  condition  of  the  steam  was  not  so  favorable  for 
economy  as  it  might  otherwise  have  been.  Doubtless  this  ex- 
plains in  part  the  poor  showing. 

116 


ENGINE  No.  27 


Head  End 


-60 


-40 


-20 


Crank  End 


-  60 


40 


-20 


I—    O 


ENGINE  No.  28. 

Simple  Condensing  Engine. 

Kind  of  engine      .     .  -   ....     ...    .     .     .     .     ."          Four  valve  (Corliss) 

Number  of  cylinders ,  1 

Diameter  of  cylinder 32i                  ins. 

Diameter  of  piston  rod 4£                  ins. 

Stroke  of  piston         .     .     .     .     .     .     .  -.     .     ..'...  5                     ft. 

Clearance     ...."......  2i                      % 

H.  P.  Constant  for  one  Ib.  m.e.p.,  one  rev.  per  minute    .  .2451          H.P. 

Condition  of  valves  and  piston  regarding  leakage    ...  Some  leakage 

Data  and  Results  of  Feed  -  Water  Test. 

Character  of  steam Ordinary 

Duration      .     .     ...'.'.-..».     .     .     .     .     .     ....     .  5.1         hrs. 

Weight  of  feed-water  consumed  .     .     .     ,     .    ' 55,001            Ibs. 

Feed-water  consumed  per  hour   .     .     ...     .     .     .     .     .     .  10,784.5         Ibs. 

Pressure  in  steam  pipe  above  atmosphere 70. 1         Ibs. 

Vacuum  in  condenser    .     ......     .     .     .     .     .     .     .  24.2         ins. 

Mean  effective  pressure .     .;    .     .     .• 38.26       Ibs. 

Revolutions  per  minute      ......     .     .     .     .     .     .  59.13 

Indicated  horse-power  . 554.4     I. H.P. 

Feed-water  consumed  per  I.  H.  P.  per  hour .     .     .     .     .     .  19.45        Ibs. 

Measurements  based  on  Sample  Diagrams. 

Initial  pressure  above  atmosphere .     .     .     67.5  Ibs. 

Corresponding  steam-pipe  pressure       ..  \.     .' 70.1  Ibs. 

Cut-off  pressure  above  zero     .     .     .    • .     .61.5  Ibs. 

Release  pressure  above  zero    .     .     .     .     .-  .     .     .     .     .          17.6  Ibs. 

Mean  effective  pressure      .     .     .     .     .     .     .     .'    .     .     .     .     38.26  Ibs. 

Back  pressure  at  mid  stroke,  below  atmosphere      .     .     .     .11.6  Ibs. 

Proportion  of  stroke  completed  at  cut-off      ,     .     .     .     .     .         .271 

Steam  accounted  for  at  cut-off     .„  ,     »     .     .     .     .  '  .     .     .     15.20  Ibs. 

Steam  accounted  for  at  release     .     .....     .     .     •  ••  "  •     15.27  Ibs. 

Proportion  of  feed-water  accounted  for  at  cut-off    .     .     .  .  .     4  .781 

Proportion  of  feed-water  accounted  for  at  release  .     .     .     .         .785 

Engine  No.  28  exhausts  into  a  jet  condenser,  with  direct 
connected  air-pump.  The  boilers  are  of  the  horizontal  return 
tubular  type.  The  steam  valves  were  practically  tight.  There 
was  some  small  amount  of  leakage  of  the  piston,  and  a  trifling 
leakage  of  the  exhaust  valves.  The  load  was  cotton  machinery. 


118 


ENGINE  No.  28 


Head  End 


-60 


-40 


-20 


60- 


40- 


Crank  End 


20- 


0- 
10— 


'^££SE  L/S':?^^ 
OK  THK       **y- 

UNIVERSITY 


ENGINE    No.  29. 


Simple  Condensing  Engine. 

Kind  of  engine 

Number  of  cylinders - .     . 

Diameter  of  each  cylinder        .,    .     .     . 

Diameter  of  each  piston  rod .     .     . 

Stroke  of  each  piston .     .    '.  .  »  , 

Clearance     .     .     .     .     .     .     .     .     .     •    .••'  «T  •     •     •     • 

H.  P.  Constant  for  one  Ib.  in.  e.  p.  one  rev.  per  minute 


Four  valve  (Corliss) 
2 

28  ins. 

4  ins. 

5  ft. 
2*  % 

.1846  H.P. 


Condition  of  valves  and  pistons  regarding  leakage Some  leakage 

Data  and  Results  of  Feed -Water  Test. 


R.  H.                     L.  H. 
CYLINDER.        CYLINDER. 

Character  of  steam  .  .  .  '  .  . 

Ordinary 

Duration  

hrs. 

5.32 

Weight  of  feed-  water  consumed  .     . 
Feed-water  consumed  per  hour     .... 
Pressure  in  steam-pipe  above  atmosphere  . 
Vacuum  in  condenser 

Ibs. 
Ibs. 
Ibs. 
ins 

76,053 
14,295.7 
67.1 
27.3 

Mean  effective  pressure  . 

Ibs. 

19.26                      31.26 

Revolutions  per  minute  .  ...  .  .  . 
Indicated  horse-power  I 

H.P. 

60.27                      60.27 
214.3                      347.8 

Indicated  horse-power,  whole  engine  .  I 
Feed-water  consumed  per  I.  H.  P.  per  hour 

H.P. 

Ibs. 

562.1 
25.43 

Measurements  Based  on  Sample  Diagrams. 


K.  H.                    L.  H. 
CYLINDER         CYLINDER. 

Initial  pressure  above  atmosphere     .     .     . 
Corresponding  steam-pipe  pressure  . 
Cut-off  pressure  above  zero                     .     . 

Ibs. 
Ibs. 
Ibs 

61.9                   63.7 
67.1 
67  7                   67.6 

Release  pressure  above  zero    .     .     . 
Mean  effective  pressure  

Ibs. 
Ibs. 

16.6                   13.9 
19.26                 31.26 

Back  pressure  at  mid  stroke,  above  or  be- 
low atmosphere  ...          .... 
Proportion  of  stroke  completed  at  cut-off  . 
Steam  accounted  for  at  cut-off     .  v  ..  .  '  •'    . 
Steam  accounted  for  at  release    .... 
Steam  accounted  for  at  cut-off,  both  cylin- 
ders, average      
Steam  accounted  for  at  release,  both  cylin- 
ders, average       
Proportion  of  feed-water  accounted  for  at 
cut-off   

Ibs. 

Ibs. 
Ibs. 

Ibs. 
Ibs. 

+2.8               —12.1 
.202                   .187 
21.82                  14.46 
24.31                  14.86 

17.27 
18.37 
.679 

Proportion  of  feed-water  accounted  for  at 
release                            

.722 

120 


ENGINE  No.    29.  121 

Engine  No.  29  has  a  pair  of  cylinders,  one  of  which  is  non- 
condensing,  and  the  other  exhausts  into  a  jet  condenser  with 
direct  connected  air-pump.  Steam  is  drawn  from  horizontal 
return  tubular  boilers,  and  is  presumably  in  a  commercially  dry 
state.  There  was  a  small  amount  of  leakage  in  the  valves  of 
both  cylinders,  not  only  steam  valves  but  exhaust  valves,  and 
some  piston  leakage.  The  engine  operated  a  cotton-mill,  work- 
ing in  connection  with  water-wheels. 


ENGINE  No.  29 


60-] 


40- 


20- 


O-1 


R.H.Cyl.  Head  End 


—20 


U  o 


-GO 


L.H.Cyl.  Head  End 


60- 
40- 
20- 

0- 
10- 


L.H.  Cyl.  Crank  End 


-40 


-20 


-  0 
-10 


ENGINE    No.  SO. 

Simple  Condensing  Engine. 

Kind  of  engine         . ....  Four  valve 

Number  of  cylinders 2 

Diameter  of  cylinder •  .  16             ins. 

Diameter  of  piston  rod 2i           ins. 

Stroke  of  piston 3               ft. 

Clearance 5                 % 

H.  P.  constant  for  one  Ib.  in.  e.  p.  one  rev.  per  min.,  each  .0361  H.P. 

Inside  diameter  of  steam  pipe    .  - 5             ins. 

Inside  diameter  of  exhaust  pipe 6             ins. 

Condition  of  valves  and  pistons  regarding  leakage     .     .  Some  leakage 

Data  and  Results  of  Feed-  Water  Test. 

Character  of  steam Ordinary 

Duration 5.            hrs. 

Weight  of  feed-water  consumed 22,055            Ibs. 

Feed- water  consumed  per  hour 4,411             Ibs. 

Pressure  in  steam  pipe  above  atmosphere 83.4          Ibs. 

Vacuum  in  condenser 26.7         ins. 

Mean  effective  pressure 31.27        Ibs. 

Revolutions  per  minute 90.4 

Indicated  horse-power 205.9    I. H.P. 

Feed- water  consumed  per  I.  H.  P.  per  hour 21.42        Ibs. 

Measurements  based  on  Sample  Diagrams. 

Initial  pressure  above  atmosphere 74.4      Ibc. 

Cut-off  pressure  above  zero 75.0      Ibs. 

Release  pressure  above  zero 14.9      Ibs. 

Mean  effective  pressure 31.16    Ibs. 

Back  pressure  at  mid  stroke  below  atmosphere — 11.15    Ibs. 

Proportion  of  stroke  completed  at  cut-off .139 

Steam  accounted  for  at  cut-off 13.81    Ibs. 

Steam  accounted  for  at  release 16.45    Ibs. 

Proportion  of  feed-water  accounted  for  at  cut-off .645 

Proportion  of  feed-water  accounted  for  at  release .761) 

Engine  No.  30  has  a  pair  of  cylinders  each  having  two  steam 
valves  and  two  exhaust  valves,  all  being  slide  valves.  The 
condenser  is  of  the  jet  type  operated  by  an  independent  air-pump 
driven  by  steam  taken  from  the  engine-pipe.  The  quantity  of 
steam  used  by  the  condenser  was  determined  by  an  independent 
test  and  allowed  for.  Steam  is  furnished  by  vertical  water 
tube  boilers,  and  a  separator  is  fitted  to  the  main  steam  pipe. 

123 


124  ENGINE   TESTS. 

No  water  collected  in  the  separator,  and  the  steam  is  presumed 
to  be  commercially  dry.  The  valves  and  pistons  of  each  cyl- 
inder showed  some  leakage.  The  load  consisted  of  dynamos 
furnishing  current  for  electric  lighting. 

Engine  No.  30  belongs  to  the  same  plant  as  Nos.  35  and  36, 
and  it  is  supplied  with  steam  from  the  same  boiler  plant. 


ENGINE  No.  3O 


80-1 


ENGINE    No.  31. 


Simple  Non-Condensing  Engine. 

Kind  of  engine 

Number  of  cylinders 

Diameter  of  each  cylinder 

Diameter  of  each  piston  rod 

Stroke  of  each  piston 

Clearance     ...........     4     .... 

H.P.  constant  for  one  Ib.  m.e.p.  one  rev.  per  minute  . 
Inside  diameter  of  steam  pipe      .     .     .  %  .     .     .     .     .     . 

Condition  of  valves  and  pistons  regarding  leakage  . 

Data  and  Results  of  Feed- Water  Tests. 


Four  valve  (Corliss) 

O 


ins. 
ins. 
ins. 


16 

21 
42 

2.5  % 

.042    H.P. 

7  ins. 

Fairly  tight 


CHARACTER  OF  LOAD. 

A. 
LIGHT  LOAD. 

B. 
HEAVY 
LOAD. 

Character  of  steam  ....  .  ...-.•'. 
Duration  ...  .  .  '  . 

hrs 

Ordinary 
4 

Ordinarv 

2 

AVeight  of  feed-water  consumed              .     . 
Feed-water  consumed  per  hour    .     .    ;  . 
Pressure  in  steam  pipe  above  atmosphere   . 
Mean  effective  pressure  .     .     .     ...     . 
Revolutions  per  minute  .     . 
Indicated  horse-power         .     .     ...    I 

Ibs. 
Ibs. 
Ibs. 

Ibs. 

H  P 

10,897. 
2,724.2 
101.8 
5.03 
87.6 
37  02 

17.746. 
8,873. 
98.6 
48.4 
84.9 
342  43 

Feed-water  consumed  per  I.  H.P.  per  hour 

Ibs. 

73.63 

25.91 

Measurements  based  on  Sample  Diagrams. 


CHARACTER  OF  LOAD. 

A. 
LIGHT  LOAD. 

. 

B. 
HEAVY 
LOAD. 

Initial  pressure  above  atmosphere      .     .     . 
Cut-off  pressure  above  zero  .     .     .     . 

Ibs. 
Ibs 

80.5 
81.9 

91.6 

94.8 

Release  pressure  above  zero      .     .     .     .    ...•• 
Mean  effective  pressure    .     ... 
Back  pres.  at  mid  stroke  above  atmosphere  . 
Proportion  of  stroke  completed  at  cut-off    . 
Steam  accounted  for  at  cut-off       .     .     .  "  .;  ; 
Steam  accounted  for  at  release       .... 
Proportion  of  feed-water  accounted  for  at 
cut-off          

Ibs. 
Ibs. 
Ibs. 

Ibs. 
Ibs. 

5.4 
2. 

.041 

28.16 

.382 

31.4 
49.26 
2.6 
.323 
20.63 
21.55 

.796 

Proportion  of  feed-water  accounted  for  at 
release                                   

.832 

Engine  No.  31  has  a  pair  of  cylinders  drawing  steam  from 
horizontal  return  tubular  boilers.  There  was  only  a  small 
amount  of  leakage  in  any  of  the  valves  and  pistons.  The 

126 


ENGINE  No.    31. 


127 


engine  was  employed  in  driving  a  line-shaft  to  which,  were 
belted  dynamos  supplying  current  for  electric  lighting. 

The  tests  reported  in  the  principal  table  were  two  in  number, 
one  of  which  was  made  with  a  friction  load  consisting  of  the 
shafting  and  empty  dynamos,  and  the  other  with  a  full  load. 

Tests  on  the  same  engine  at  intermediate  loads  gave  the  fol- 
lowing principal  results  : 


INDICATED 
HORSE 
POWER. 

FEED-WATER 
PEK  I.H.P. 
PER  HOUR. 

PROPORTION 
OF  STROKE 
COMPLETED 
AT  CUT-OFF. 

PROPORTION 
OF  FEED- 
WATER  ACCT. 
FOR  AT  CUT- 
OFF. 

100.4 

38.38 

.084 

.509 

146.2 

31.43 

.121 

.588 

222.2 

25.83 

.178 

.709 

287.1 

25.39 

.231 

.745 

ENGINE  No.  31a. 


RH.Cyl. Head  End 


L.H.Cyl.HeadEnd 


L-   0 


-100 
-80 
-60 
40 
-20 
-  0 


L.H.Cyl. Crank  End 


-60 

40 

-20 

-  0 


ENGINE  No.Slb 


L.H.Cyl.Head  End 


L.H.Cyl. Crank  End 


-80 

-60 

-40 

-20 

-  0 
-80 
-60 
-40 
-20 

-  O 


FEED -WATER   TESTS. 


COMPOUND    ENGINES. 

[  These  engines  are  all  of  the  automatic  cut-off  type,  with  fly-ball  governor, 
unless  otherwise  stated.] 


181 


ENGINE    No.  32. 


Compound  Condensing  Engine. 


H.  P. 
CYLINDER. 

L.  P. 
CYLINDER. 

Kind  of  engine 

ins. 
ins. 
ft. 

% 

H.P. 

ins. 
ins. 

Four  valv 
1 
26 
4 
4 
3 

.159 
1 
8 
14 

Fairly  tight 

e  (Corliss) 
1 
48 
5 
4 
3 

.5454 
3.43 
14 
14 

Tight 

^Number  of  cylinders  . 

Diameter  of  cylinders      .     .-.•'. 
Diameter  of  piston  rod    
Stroke  of  piston                                .... 

Clearance  

H.  P.  constant  for  1  Ib.  m.  e.  p.  one  rev- 
olution per  miu  
Ratio  of  areas  of  cylinders       
Inside  diameter  of  steam  pipe  
Inside  diameter  of  exhaust  pipe    .... 
Condition  of  valves  and  pistons  regarding 
leakage 

Data  and  Results  of  Feed  -Water  Test. 

Character  of  steam      .     .-..;• .  .,     . 

Duration  .     .     .     .     .  • .     /    t     . 

Weight  of  feed-water  consumed     ....     .     .     .     .     . 

Feed-water  consumed  per  hour .  .     .     . 

Pressure  in  steam  pipe  above  atmosphere    .     .     .     .... 

Pressure  in  receiver .     . 

Vacuum  in  condenser 

Revolutions  per  minute .     .     . 

Mean  effective  pressure,  H.  P.  cylinder 

Mean  effective  pressure,  L.  P.  cylinder 

Indicated  horse-power,  H.  P.  cylinder 

Indicated  horse-power,  L.  P.  cylinder 

Indicated  horse-power,  whole  engine 

Feed-water  consumed  per  I.  H.  P.  per  hour 


Ordinary 


4.5 

hrs. 

*44,436 

Ibs. 

9,874 
94.8 

Ibs. 
Ibs. 

6.4 

Ibs. 

27.2 

ins. 

52.3 

41.14 

Ibs. 

9.27 

Ibs. 

342.1 

H.P. 

264.43 

H.P. 

606.53 

H.P. 

*16.28 

Ibs. 

Measurements  based  on  Sample  Diagrams. 


H.P. 
CYLINDER. 

L.  P. 
CYLINDER. 

Initial  pressure  above  atmosphere  . 

Ibs. 

89.4 

6.0 

Corresponding  steam-pipe  or  receiver 

pressure   ...                          .     . 

Ibs. 

94.2 

6.3 

Cut-off  pressure  above  zero    .... 

Ibs. 

91.9 

12.6 

Release  pressure  above  zero  .... 

Ibs. 

28.4 

7.5 

Mean  effective  pressure      

Ibs. 

41.26 

9.28 

Back  pressure  at  mid  stroke,  above  or 

below  atmosphere  

Ibs. 

+  8.1 

-  10.8 

Proportion  of  stroke  completed  at  cut-off 

.305 

.544 

Steam  accounted  for  at  cut-off    . 

Ibs. 

12.60 

11.78 

Steam  accounted  for  at  release  . 

Ibs. 

12.84 

12.98 

Proportion  of  feed-water  accounted  for 

at  cut-off  

.774 

.723 

Proportion  of  feed-water  accounted  for 

at  release       

.789 

.797 

Includes  steam  used  by  circulating-pump. 

133 


134  ENGINE    TESTS. 

Engine  No.  32  is  a  cross-compound,  having  unjacketed  hori- 
zontal cylinders 'and  unjacketed  receiver.  A  surface  condenser 
is  employed,  and  the  air-pump  is  operated  by  direct  connection 
with  the  engine.  The  circulating-pump  is  a  duplex  steam 
pump  9"  x  10"  x  12",  and  the  steam  it  used  is  included  in  that 
reported.  The  engine  is  furnished  with  steam  from  sectional 
boilers,  and  it  is  presumed  to  be  in  a  commercially  dry  condi- 
tion. In  the  matter  of  leakage  the  engine  was  in  excellent 
condition  throughout  with  the  exception  of  the  piston  in  the 
high-pressure  cylinder,  which  leaked  a  small  amount.  The 
load  consisted  of  a  cotton-mill.  The  feed-water  consumption 
was  determined  by  measuring  the  water  discharged  by  the  air- 
pump. 


ENGINE  No.  32 


H.P.  Head  End 


H,P.  Crank  End 


—  100 

—  80 

—  60 
-40 

—  20 
L—   0 

r— 100 

-80 
—60 

—  40 
—20 

—  0 


5- 
0- 
5- 
10- 


L,P.  Head  End 


5- 

o- 

5- 
10- 


L,P.  Crank  End 


ENGINE    No.  33. 

Compound  Condensing  Engine. 


\ 

H.P. 
CYLINDER. 

L.  P. 

CYLINDER. 

Kind  of  engine       .     ...     .     . 

Single 

valve. 

Number  of  cylinders  .     .     ... 

1 

1 

Diameter  of  cylinder       ....     ins. 

12 

20 

Stroke  of  piston                ....     ins 

12 

12 

Clearance      % 

33 

9 

H.  P.  Constant  for  one  Ib.  m.  e.  p. 

one  rev.  per  min  H.P. 

.00342 

.00952 

Ratio  of  areas  of  cylinders  . 

1 

2.78 

Condition  of   valves  and    pistons 

regarding  leakage     .... 

Tight. 

Tight. 

Data  and  Results  of  Feed -Water  Tests. 


TEST. 
CONDITIONS  REGARDING  USE  OF  CONDENSER. 

A. 

CONDENSING 

B. 

NON- 
CONDENSING 

Character  of  steam     

Ordinary 

Ordinary 

Duration       hrs. 

8 

8 

Weight  of  feed-water  consumed    .    Ibs. 

34,555 

41,562 

Feed-water  consumed  per  hour     .    Ibs. 

4,319.4 

5,195 

Press,  in  steam  pipe  above  atmos.    Ibs. 

129.3 

128 

Vacuum  in  condenser     ....    ins. 

25 

Revolutions  per  minute  .... 

300. 

296.1 

Mean  effective  pressure,  H.P.  cyl.    Ibs. 

53.53 

57.21 

Mean  effective  pressure,  L.P.  cyl.    Ibs. 

20.73 

20.34 

Indicated  horse-power,  H.P.  cyl.    H.P. 

109.84 

115.85 

Indicated  horse-power,  L.  P.  cyl.  H.P. 

118.41 

114.69 

Indicated  H.  P.,  whole  engine      .  H.P. 

228.25 

230.54 

Feed-water  cons,  per  I.  H.P.  per  hr.    Ibs. 

18.92 

22.53 

The  above  are  the  totals  and  averages  for  the  two  engines. 
Measurements  based  on  Sample  Diagrams. 


TESTS. 

H.P.CYL. 

L.P.  CYL. 

H.P.CYL. 

L.P.  CYL. 

Initial  pressure  above  atmosphere    Ibs. 

122.9 

33.9 

121.5 

52.8 

Corresponding  steam  -pipe  pressure    Ibs. 

132. 

136. 

Cut-off  pressure  above  zero     .     .     Ibs. 

122. 

27.1 

124.3 

35.8 

Release  pressure  above  zero     .     .     Ibs. 

67.9 

17.8 

82.3 

27.4 

Mean  effective  pressure       ...     Ibs. 

53.4 

20.71 

56.44 

20.25 

Back  pressure  at  mid  stroke  above 

i 

or  below  atmosphere       .     .     Ibs. 

+  20.3 

—11.       '+29.4 

+  1.1 

Proportion     of  stroke  completed 

j         ,.  • 

at  cut-off  

.38 

.521]         .532 

.66 

Steam  accounted  for  at  cut-off     .     Ibs. 

15.21 

12.14 

20.13 

16.54 

Steam  accounted  for  at  release    .     Ibs. 

16.24 

1321 

28.2 

17.76 

Proportion  of  feed  water  account- 

ed for  at  cut-off     .     .     ..    . 

.804 

.642 

.894 

.734 

Proportion  of  feed  water  account- 

ed for  at   release    .     .     .     . 

.859 

.700 

.925 

.789 

136 


ENGINE  No.    33.  137 

Engine  No.  33  consists  of  two  independent  engines  which 
w^ere  tested  simultaneously.  These  engines  are  single-acting 
with  vertical  unjacketed  cylinders,  and  provided  with  a  single 
piston  valve  fitted  with  ring  packing,  one  valve  serving  for 
both  high-  and  low-pressure  cylinders.  A  jet  condenser  is  used 
which  is  common  to  both  engines  ;  and  it  is  operated  by  an  inde- 
pendent air-pump,  which  takes  steam  from  the  main  supply 
pipe.  The  boiler  feed-pump  is  also  supplied  from  the  main 
pipe.  The  quantity  of  steam  used  by  these  two  pumps  was 
determined  by  independent  tests  and  allowed  for.  Steam  is 
furnished  by  water  tube  boilers  ;  and  a  calorimeter  test  showed 
in  one  case  ^  of  1  %  of  moisture,  and  in  the  other  ITL  % .  The 
valves  and  pistons  of  both  engines  were  practically  tight.  The 
load  consisted  of  dynamos  employed  in  electric  lighting.  One 
test  was  made  with  the  engines  running  condensing,  and  an- 
other running  non-condensing,  the  condenser  being  stopped. 

The  difference  in  economy  of  these  engines,  due  to  the  use 
of  a  condenser  not  allowing  for  steam  used  by  air-pump,  is 
represented  by  3.61  Ibs.  of  feed-water  per  I.  H.  P.  per  hour, 
which,  in  round  numbers,  is  20  <%  of  the  quantity  used  when 
the  engine  was  run  condensing.  The  results  of  these  tests  can- 
not be  passed  by  without  noticing  the  marked  difference  in  the 
porportion  of  steam  accounted  for  at  the  cut-off  under  the  two 
conditions  of  operation  ;  and  the  loss  of  steam  between  the 
high-pressure  cylinder  and  low-pressure  cylinder  in  both  cases. 


<P§6  L'BR^> 

~  OF    THK 

UNIVERSITY 


ENGINE  No.  33a 


H.P.  17 


L.P.  17 


—  120 


-  30 


—  40 


0 
—  40 


—  20 


—  0 

—  10 


120- 


80- 


40- 


H.P.  24 


,  ENGINE  No.  33b 


H,P.  17 


L.P.  17 


i—  120 


-   80 


-    40 


-    20 


—     0 


120—1 


80- 


40- 


H.P.  24 


40- 


20- 


L.P.  24 


ENGINE    No.   34. 

Compound  Condensing  Engine. 


H.P.  CYLINDER. 

L.P.  CYLINDER. 

Kind  of  engine  .  .  .-,.  .  .  .  . 
Number  of  cylinders  ,  .  .  .  .  . 
Diameter  of  cylinder 

ins. 
ins. 
ft. 

% 

H.P. 

ins. 
ins. 

Four  valv 
1 
22 
31 
5 
2.2 

.1138 
1 

7 
9 

Some  leakage 

B  (Corliss) 
1 
44 
31 
5 
5.9 

.4592 
4.04 
13 
16 
Practically 
tight 

Diameter  of  piston  rod  
Stroke  of  piston  .... 

Clearance  

H.  P.  constant  for  one  Ib.  in.  e.  p.  one 
rev.  per  min  
Ratio  of  areas  of  cylinders     .... 
Inside  diameter  of  steam  pipe     .     .     . 
Inside  diameter  of  exhaust  pipe       .     . 
Condition  of  valves  and  pistons  regard- 
ing leakage   

Data  and  Results  of  Feed  -  Water  Test. 

Character  of  steam 

Duration 

Weight  of  feed-water  consumed    .     .     ....     .  .  .     . 

Feed-water  consumed  per  hour     .     .     .     .     .     .     .     .     . 

Pressure  in  steam  pipe  above  atmosphere  .     .....'.     .". 

Pressure  in  receiver  above  atmosphere 

Vacuum  in  condenser    .     .     .     .     .     ;  .  i     ...     ...     , 

Revolutions  per  minute ... 

Mean  effective  pressure  H.  P.  cylinder *, 

Mean  effective  pressure  L.  P.  cylinder       .     .     .     ...     , 

Indicated  horse-power  H.  P.  cylinder ,     . 

Indicated  horse-power  L.  P.  cylinder    .     .     .v  .     .     .     .   ., 
Indicated  horse-power,  whole  engine    .     .     .    „.     .  .  . 
Feed-water  consumed  per  I.  H.  P.  per  hour    .     .     .'-...., 


Ordinary 

4 

hrs. 

33,813 

Ibs. 

8,453.2 

Ibs. 

116.1 

Ibs. 

7.5 

Ibs. 

25.5 

ins. 

68.08 

41.48 

Ibs. 

10.08 

Ibs. 

321.39 

H.P. 

315.09 

H.P. 

636.48 

H.P. 

13.28 

Ibs. 

Measurements  based  on  Sample  Diagrams. 


H.  P. 
CYLINDER. 

L.P. 

CYLINDER. 

Initial  pressure  above  atmosphere  .     .     Ibs. 

108.8 

9.1 

Corresponding  steam-pipe  or  receiver 

pressure   Ibs. 

114.2 

7.4 

Cut-off  pressure  above  zero    .     .     .  -".     Ibs. 

104. 

16.7 

Release  pressure  above  zero  .     „     .    ;.     Ibs. 

29.1 

6.8 

Mean  effective  pressure     Ibs. 

41.26 

10.05 

Back  pressure  at  mid  stroke  above  or 

below  atmosphere       Ibs. 

+  11.3 

-  11.8 

Proportion  of  stroke  completed  at  cut-off 

.26 

.325 

Steam  accounted  for  at  cut-off    .     .     .     Ibs. 

10.48 

10.06 

Steam  accounted  for  at  release  .     .     .     Ibs. 

11.3 

10.98 

Proportion  of  feed-water  accounted  for 

.789 

.758 

Proportion  of  feed-water  accounted  for 

at  release                      

.852 

.827 

140 


ENGINE  No.  34-  141 

Engine  No.  34  is  a  cross  compound  with  horizontal  jacketed 
cylinders  and  uiijacketed  receiver.  Steam  supplied  to  the  low- 
pressure  cylinder  first  circulates  through  the  jacket  space, 
entering  at  the  bottom  at  a  central  opening.  The  jackets  are 
drained  into  tanks,  which  are  emptied  by  means  of  pumps 
operated  by  the  engine.  The  water  of  condensation  from  this 
source  during  the  tests  amounted  to  600  Ibs.  per  hour,  or 
about  7  %  of  the  total  quantity  of  steam  used  by  the  engine. 
The  condenser  is  of  the  jet  type  with  a  direct  connected  air- 
pump.  Steam  is  supplied  from  horizontal  return  tubular  boil- 
ers. A  calorimeter  test  showed  that  the  amount  of  moisture 
was  T2o  of  1  %.  The  exhaust  valves  and  pistons  of  both 
cylinders,  and  the  steam  valves  of  the  low-pressure  cylinder 
were  found  to  be  practically  tight.  The  steam  valves  of  the 
high-pressure  cylinder  showed  some  leakage.  The  load  con- 
sisted of  cotton  machinery. 


OF   THB 

UNIVERSITY 


ENGINE  No.  34 


H.P.  Head  End 


I0n 

5- 
0- 

5- 
10- 


L.P.  Head  End 


10— 

5- 
0- 

5- 
10- 


L.P.  Crank  End 


ENGINE    No.  35. 

Compound  Condensing  Engine. 


H.  P. 
CYLINDER. 


L.  P. 

CYLINDER. 


Kind  of  engine Single  valve. 

Number  of  cylinders      .',..:.  1                            1 

Diameter  of  cylinder     .     .     ...     •  ins.            13  22 

Diameter  of  piston  rod       .     ."    .     .     .  ins.              lit                        2S 

Stroke  of  piston ins.           18 

Clearance ...  %             7  10 

Horse-power  constant  for  one  Ib.  in.e.p. 

one  revolution  per  minute    .     .     .  H.P.  I             .0119                    .0344 
Ratio  of  areas  of  cylinders     ....                                                  2.89 

Inside  diameter  of  steam  pipe     .     .     .  ins.             4£ 

Inside  diameter  of  exhaust  pipe       .     .  ins.                                          6. 

Condition  of  valves  and  pistons  regard-  Considerable       Considerable 

ing  leakage leakage  leakage 

Data  and  Results  of  Feed- Water  Test. 

Character  of  steam  .     .     .     .     ...     •     ...     •     •     ...     .  Ordinary 

Duration   ..../.... 5  hrs. 

Weight  of  feed-water  consumed     .     . 16,375  Ibs. 

Feed-water  consumed  per  hour .     .  3,275  Ibs. 

Pressure  in  steam  pipe  above  atmosphere     ........  105.2  Ibs. 

Vacuum  in  condenser       .     .     ...     .     .     .     .     ....     .  28  ins. 

Revolutions  per  minute ........  197.1 

Mean  effective  pressure  H.  P.  cylinder 32.57  Ibs. 

Mean  effective  pressure  L.  P.  cylinder 10.63  Ibs. 

Indicated  horse-power  H.  P.  cylinder      .......'.  76.4  H.P. 

Indicated  horse-power  L.  P.  cylinder      .     .  *.     ,     .     .     .     .  72.1  H.P. 

Indicated  horse-power,  whole  engine       .     .     .     ^     .     .     .     .  148.5  H.P. 

Feed-water  consumed  per  I.  H.  P.  per  hour      ...;..  22.05  Ibs. 

Measurements  based  on  Sample  Diagrams. 


H.  P. 
CYLINDER. 


L.  P. 
CYLINDER. 


Initial  pressure  above  atmosphere  . 
Corresponding  steam-pipe  or   receiver 

pressure  ......... 

Cut-off  pressure  above  zero    ...     . 

Release  pressure  above  zero  .... 

Mean  effective  pressure     .     .     .     .    -..  . 

Back  pressure  at  mid  stroke  above  or 

below  atmosphere 

Proportion    of     stroke    completed    at 

cut-off 

Steam  accounted  for  at  cut-off  ...  . 
Steam  accounted  for  at  release  .  .  . 
Proportion  of  feed-water  accounted  for 

at  cut-off 

Proportion  of  feed-water  accounted  for 

at  release 


!43 


Ibs. 

Ibs. 
Ibs. 
Ibs. 
Ibs. 


104 
84.6 
43.6 
33.21 


Ibs.  I     +18 


Ibs. 
Ibs. 


.382 
13.73 
14.95 

.623 
.678 


11.5 

16.9 
11. 

10.82 

-9.5 

.505 
13.93 
14.68 

.632 
.666 


144  ENGINE    TESTS. 

Engine  No.  35  is  a  horizontal  cross-compound  unjacketed 
engine,  provided  with  a  shaft  governor  operating  on  the  cut-off 
of  the  high-pressure  cylinder.  The  valves  are  of  the  piston 
type  without  packing.  A  jet  condenser  is  used  operated  by  an 
independent  air-punip  driven  with  steam  taken  from  the  engine 
pipe.  The  quantity  thus  used,  as  also  that  consumed  by  the 
boiler  feed-pump,  was  determined  by  independent  tests  and 
allowed  for.  Steam  is  supplied  from  vertical  water- tube  boil- 
ers, and  a  separator  placed  in  the  steam  pipe  secured  what  was 
believed  to  be  commercially  dry  steam.  The  steam  showed  no 
superheating.  The  valve  in  each  cylinder  was  found  to  leak 
badly.  The  piston  of  the  high-pressure  cylinder  was  fairly 
tight.  Owing  to  the  leakage  of  the  low-pressure  valve  no 
leakage  observations  could  be  made  upon  the  low-pressure 
piston.  The  load  consisted  of  dynamos  furnishing  current  for 
electric  lighting. 

There  is  a  close  agreement  between  the  steam  accounted  for 
by  the  indicator  in  the  two  cylinders,  which  might  be  surprising 
in  view  of  the  fact  that  the  cylinders  are  unjacketed,  were  it 
not  known  that  the  steam  valve  of  the  high-pressure  cylinder 
showed  considerable  leakage.  Some  of  the  steam  shown  on 
the  low-pressure  diagram  was  undoubtedly  due  to  this  cause. 


ENGINE  No.  35 


IOO-, 
80- 
60- 
40- 
20- 
0- 


OF   THE 

UNIVERSITY 


H.P.  Head  End 


H. P.  Crank  End 


r-IOO 
80 

—  60 

—  40 

—  20 

—  0 


L.P.  Head  End 


-  10 

-  5 
—    0 

-  5 

-  10 


10-, 
5- 
0- 
5- 

10- 


L.P.  Crank  End 


ENGINE    No.  36. 

Compound  Condensing  Engine. 


H.  P. 

CYLINDER. 

L.  P. 

CYLINDER. 

Kind  of  engine  
lumber  of  cylinders 

ins. 
ins. 

ft. 

% 

H.P. 

ins. 
ins. 

Four  valve 
1 
16 
3 
4 
2 

.0479 
1.00 
6 

Practice 

(Corliss) 
1 
32 
311 
4 
4 

.1937 
4.04 

12 
lly  tight 

Diameter  of  cylinder 

Diameter  of  piston  rod  

Stroke  of  piston  

Clearance  . 

H.  P.  constant  for  one  Ib.  m.  e.  p.  one 
revolution  per  minute     .... 
Ratio  of  areas  of  cylinders     .... 
Inside  diameter  of  steam  pipe     .     .     . 
Inside  diameter  of  exhaust  pipe    '  .     . 
Condition  of  valves  and  pistons  regard- 
ing leakage   

Data  and  Results  of  Feed -Water  Test. 


Character  of  steam 

Duration 

Weight  of  feed-water  consumed 

Feed-water  consumed  per  hour 

Pressure  in  steam  pipe  above  atmosphere  . 
Pressure  in  receiver  above  atmosphere       .     . 

Vacuum  in  condenser 

Revolutions  per  minute 

Mean  effective  pressure,  H.  P.  cylinder  .  . 
Mean  effective  pressure,  L.  P.  cylinder  .  . 
Indicated  horse-power,  H.  P.  cylinder  .  . 
Indicated  horse-power,  L.  P.  cylinder  .  . 
Indicated  horse- power,  whole  engine  .  .  . 
Feed-water  consumed  per  I.  H.  P.  per  hour  . 


Ordinary 

5.05      hrs. 

27,133  Ibs. 

5,373  Ibs. 

126.8         Ibs. 


27.4 
74.9 
58.29 
11.79 
211.6 
170.9 
382.5 
14.05 


Ibs. 

Ibs. 
H.P. 
H.P. 
H.P. 

Ibs. 


Measurements  based  on  Sample  Diagrams. 


H.P. 

CYLINDER. 

L.  P. 

CYLINDER. 

Initial  pressure  above  atmosphere  .     . 
Cut-off  pressure  above  zero    .... 
Release  pressure  above  zero  .... 
Mean  effective  pressure 

Ibs. 
Ibs. 
Ibs. 
Ibs 

116.5 
120.7 
39.4 
59  4 

7 
18.4 
7.4 
11.97 

Back  pressure  at  mid  stroke,  above  or 
below  atmosphere  
Proportion  of  stroke  completed  at  cut-off 
Steam  accounted  for  at  cut-off    .     . 
Steam  accounted  for  at  release   .     . 
Proportion  of  feed-water  accounted  for 
at  cut-off       .          

Ibs. 

Ibs. 
Ibs. 

+  9.9 
.295 
10.78 
12. 

.767 

-13. 
.337 
8.98 
10.42 

.64 

Proportion  of  feed-water  accounted  for 
at  release 

853 

.741 

146 


ENGINE   No.  36.^<^  147 


Engine  No.  36  is  a  cross-compound  horizontal  engine  with 
steam  jacketed  cylinders  and  a  jet  condenser  operated  by  a 
direct  connected  air-pump.  The  jacket  spaces  in  each  cylinder 
form  a  thoroughfare  through  which  the  steam  is  supplied  to  the 
respective  steam  chests,  the  steam  first  entering  the  bottom  of 
the  jacket  at  a  central  point.  During  the  test  the  drain-pipes 
provided  for  carrying  off  the  water  of  condensation  were  closed, 
and  all  this  water  passed  over  into  the  cylinder.  Whatever 
effect  the  jackets  might  otherwise  have  produced  was  thus 
nullified,  and  the  engine  may  be  considered  as  practically  un- 
jacketed.  Steam  is  supplied  from  vertical  water  tube-boilers, 
and  a  separator  is  provided  in  the  main  steam  pipe.  For  a 
short  period  during  the  test,  water  accumulated  in  the  sepa- 
rator, and  its  quantity  was  determined  and  allowed  for.  For 
the  balance  of  the  test  there  was  no  accumulation,  and  the 
steam  is  presumed  to  be  commercially  dry.  The  valves  and 
pistons  of  both  cylinders  were  practically  tight.  The  load 
consisted  of  dynamos  supplying  current  for  electric  lighting. 

Engine  No.  36  belonged  to  the  same  plant  as  Nos.  30  and  35. 

The  behavior  of  the  steam  in  its  passage  through  the  cylin- 
ders which  the  analysis  of  the  indicator  diagrams  reveals  is  of 
unusual  interest.  The  increase  in  the  amount  of  steam  shown 
at  release  over  cut-off  is  very  large  in  both  cylinders,  and  the 
loss  of  steam  which  the  low-pressure  cylinder  shows  is  a  marked 
feature.  These  actions  may  be  attributed  to  the  effect  of  the 
jacket-water  in  the  cylinders  combined  with  the  cooling  action 
which  always  takes  place  when  steam  parses  from  a  high  to  a 
low-pressure  cylinder,  where  no  means  is  provided  for  reducing 
•cylinder  condensation.  In  this  case  the  quantities  are  unaf- 
fected by  steam  which  leaked,  all  the  valves  and  pistons  being 
practically  tight. 


OF   THK 

UNIVERSITY 


ENGINE  No.  36 


120- 
100- 
80- 
60- 
40- 
20- 
0- 


H.P.  Head  End 


H.P.  Crank  End 


120 
100 
-80 
-60 
-40 
-20 
-  0 


10- 
5 

o- 

6- 
10- 


L.P.  Head  End 


L.P.  Crank  End 


-  10 

-  5 

-  0 

-  5 


ENGINE   No.  37. 


Compound  Condensing  Engine. 


H.P. 
CYLINDER. 

L.  P. 

CYLINDER. 

Kind  of  engine                          .... 

Four  valve 

(Corliss) 

Number  of  cylinders      .          .... 

1 

Diameter  of  cylinder     ins. 
Diameter  of  piston  rod       ins. 

Stroke  of  piston  ft. 
Clearance   % 
H.  P.  constant  for  1  Ib.  m.  e.  p.  one 
revolution  per  minute    ....  H.P. 

16* 
2J 

4£ 
2* 

.0573 

32 
121 
f« 

4* 
2* 

.2162 

Ratio  of  areas  of  cylinders     .... 
Condition  of  valves  and  pistons  regard- 
ing leakage   

1 
Fairly  tight. 

3.774 

Data  and  Results  of  Feed-  Water  Test. 

Character  of  steam 

Duration 

Weight  of  feed-water  consumed 

Feed-water  consumed  per  hour 

Pressure  in  steam  pipe  above  atmosphere 

Pressure  in  receiver  above  atmosphere 

Vacuum  in  condenser 

Revolutions  per  minute 

Mean  effective  pressure,  H.  P.  cylinder 

Mean  effective  pressure,  L.  P.  cylinder 

Indicated  horse-power,  H.  P.  cylinder 

Indicated  horse-power,  L.  P.  cylinder 

Indicated  horse-power,  whole  engine 

Feed-water  consumed  per  I.  H.  P.  per  hour 


Ordinary 

0.833 

hrs. 

3,122. 

Ibs. 

3,746 

Ibs. 

108 

Ibs. 

2 

Ibs. 

27 

ins. 

59 

45.47 

Ibs. 

9.83 

Ibs. 

154.28 

H.P. 

125.85 

H.P. 

280.13 

H.P. 

13.37 

Ibs. 

Measurements  based  on  Sample  Diagrams. 


H.P. 

CYLINDER. 

L.  P. 
CYLINDER. 

Steam  accounted  for  at  cut-off    .     ,     .     Ibs. 
Steam  accounted  for  at  release    .     .     .     Ibs. 
Proportion  of  feed-water  accounted  for 
at  cut-off 

9.8 

10.78 

732 

10.48 
10.94 

784 

Proportion  of  feed-water  accounted  for 
at  release 

806 

818 

Engine  No.  37  is  a  tandem  horizontal  compound  with  cylin- 
ders and  heads  steam  jacketed.  The  condenser  is  of  the  jet 
type,  operated  with  an  air-pump  connected  to  the  engine. 

149 


150  ENGINE    TESTS. 

Steam  is  supplied  from  vertical  boilers,  which  gave  steam  that 
was  at  times  slightly  superheated,  and  at  other  times  in  its  ordi- 
nary condition.  The  feed-water  was  measured  on  the  test  by 
water-glass  observations,  the  water  being  first  pumped  to  a  high 
point,  then  shut  off,  and  the  test  continued  until  the  boilers 
needed  replenishing.  The  water  drained  from  the  jackets 
amounted  to  248  Ibs.  per  hour,  or  in  round  numbers,  7%  of  the 
total  quantity  used  by  the  engine.  The  load  consisted  mainly 
of  rubber  grinding  machinery. 

The  variable  character  of  the  load,  and  the  short  duration  of 
the  test,  make  the  results  less  accurate  than  they  would  be 
if  the  load  had  been  steady  and  the  water  had  been  measured 
for  a  longer  period.  The  sample  indicator  diagrams  which  are 
here  presented,  owing  to  the  fluctuating  load,  must  be  regarded 
as  showing  the  general  distribution  of  the  steam  in  the  cylin- 
ders rather  than  precise  average  samples  of  the  work. 

When  the  jackets  were  shut  off,  the  distribution  of  the 
steam  was  affected  in  a  noticeable  degree.  The  difference 
between  the  steam  shown  at  release  and  cut-off  was  greatly 
increased. 


ENGINE  No.  37 


H.P.  Head  End 


[-100 
-80 
-60 
-40 
-20 
-  0 


H.P.  Crank  End 


-100 
-80 
-60 
-40 
-20 
-  0 


5- 

O- 

5- 

10- 


L.P.  Head  End 


5- 
0- 
5- 
10- 


L.P.  Crank  End 


ENGINE  No.  38. 


Compound  Condensing  Engine. 


-  

H.P. 
CYLINDER. 

L.  P. 
CYLINDER. 

Kind  of  engine     
Number  of  cylinders      
Diameter  of  cylinder     ins. 
Diameter  of  piston  rod       ins. 
Stroke  of  piston  .                                   .       ft. 

Four  valve 
1 
22 
3.5 
5 
2.5 

.0114 
1 

Practically 
tight 

(Corliss) 
1 
44 
3.5 
5 
2.5 

.0459 
4.03 

Excessive 
leakage 

Clearance   % 
H.  P.  Constant  for  one  Ib.  m.e.p.,  one 
rev.  per  minute      H.P. 
Ratio  of  areas  of  cylinders     .... 
Condition  of  valves  and  pistons  regard- 
ing leakage   . 

Data  and  Results  of  Feed  -Water  Test. 
Character  of  steam                                   -                       Ord 

inary 
hrs. 
Ibs. 
Ibs. 
Ibs. 
Ibs. 
ins. 

Ibs. 
Ibs. 
H.P. 
H.P. 
H.P. 
Ibs. 

Duration           .                         

.      .                 8.58 

Weight  of  feed-  water  consumed  
Feed-water  consumed  per  hour    
Pressure  in  steam  pipe  above  atmosphere  
Pressure  in  receiver                                      

.     .     118,927 
.     .       13,861 
.     .            108.9 
.     .                8.4 

Vacuum  in  condenser                         .          

.     .              23.6 
.     .              62.14 
.     .              61.53 

.     .                9.87 

Revolutions  per  minute       
Mean  effective  pressure,  H.  P.  cylinder     
Mean  effective  pressure  L   P   cylinder 

Indicated  horse-power   H   P   cylinder 

.     .            434.6 

Indicated  horse-power,  L.  P.  cylinder  
Indicated  horse-power,  whole  engine     
~Ffip.rUwat,p.r  Consumed  ner  I.  H.  P.  Der  hour  . 

.     .            281.4 
.     .            716 
19.36 

Measurements  Based  on  Sample  Diagrams. 


H.P. 
CYLINDER. 

L.  P. 
CYLINDER. 

Initial  pressure  above  atmosphere  .     . 
Cut-off  pressure  above  zero    .... 
Release  pressure  above  zero  .... 
Mean  effective  pressure 

Ibs. 
Ibs. 
Ibs. 
Ibs. 

112 
111 
45.7 

62.08 

8 
1-6.8 
6.2 
9.84 

Back  pressure  at  mid  stroke  above  or 
below  atmosphere       

Ibs. 

+  10 

—  11 

Proportion    of     stroke    completed    at 
cut-off      
Steam  accounted  for  at  cut-off   .     .     . 
Steam  accounted  for  at  release  .     .     . 
Proportion  of  feed-water  accounted  for 

Ibs. 
Ibs. 

.377 
13.07 
12.76 

.675 

.381 
8.42 
8.67 

.435 

Proportion  of  feed-water  accounted  for 
at  release      

.^____  _____  __^__  —  —  —  —  —  —  ^—  —  —  — 

.659 

.448 

152 


ENGINE  No.  38.  153 

Engine  No.  38  is  a  horizontal  cross  compound.  The  cylin- 
ders are  steam-jacketed,  and  the  intermediate  receiver,  which  is 
a  chamber  30"  in  diameter  and  8"  high,  is  also  jacketed.  The 
arrangement  of  the  jacket^piping  is  such  that  the  drain  pipe  of 
the  high-pressure  jacket  supplies  the  low-pressure  jacket,  and 
the  drain  pipe  of  this  supplies  the  receiver  jacket,  and  their 
sizes  are  so  proportioned  that  there  is  a  continual  reduction  of 
pressure  from  one  point  to  the  next,  and  consequently  a  con- 
tinuous circulation.  The  engine  is  fitted  with  a  jet  condenser 
operated  by  a  direct  connected  air-pump.  Steam  is  furnished 
by  horizontal  return  tubular  boilers  located  at  a  distance  of 
some  200  feet.  The  water  of  condensation  which  collects  in 
the  steam  pipe  is  carried  back  to  a  feed  tank  in  the  boiler-room, 
and  steam  used  by  the  feed  pump  exhausts  into  the  same  tank. 
There  was  some  leakage  of  joints  in  the  steam  piping  which 
has  not  been  allowed  for.  The  valves  and  pistons  of  the  high- 
pressure  cylinder  were  practically  tight.  The  valves  of  the 
low-pressure  cylinder  were  tight,  but  the  piston  contained  a 
loosely  fitting  packing  ring  and  leaked  very  badly.  The  load 
consisted  of  cordage  machinery. 

The  interest  in  this  test  centers  upon  the  effect  which  was 
produced  by  excessive  leakage  through  the  low-pressure  piston. 
In  a  well  jacketed  engine  the  steam  accounted  for  by  the  indi- 
cator is  nearly  as  great  in  the  low-pressure  cylinder  as  in  the 
high  pressure  cylinder.  In  this  case  there  is  a  reduction  from 
.675  to  .435,  or  24%  of  the  total  weight  of  steam  consumed, 
and  this  is  evidently  due  to  the  leakage  referred  to. 


ENGINE  No.  38 


120^ 

100- 

80- 

60- 

40- 

20- 

0- 


H.P.  Head  End 


H.P.  Crank  End 


-120 
-100 
-  80 
—  60 
—40 
—20 
0 


L.P.  Head  End 


10 

-  5 

-  0 

-  5 

-  10 


10 

5  - 
0- 

6  - 
10  — 


L.P.  Crank  End 


ENGINE    No.  39. 

Compound  Condensing  Engine. 


H.  P. 
CYLINDER. 

L.  P. 

CYLINDER. 

Kind  of  engine                                .     • 

Single 

valve 

Number  of  cylinders      

1 

Diameter  of  cylinder     ins. 

13 

26 

Diameter  of  piston  rod                                 ins 

lit 

2* 

Stroke  of  piston                                             ins 

18 

18 

Clearance                                                          % 

7 

10 

Horse-power  constant  for  one  Ib.  m.e.p. 

one  revolution  per  minute    .     .     .  H.P. 

.0019 

.048 

Ratio  of  areas  of  cylinders      .... 

1 

4.03 

Condition  of  valves  and  pistons  regard- 

Considerable 

Considerable 

ing  leakage   

leakage 

leakage 

Data  and  Results  of  Feed -Water  Test. 

Character  of  steam 

Duration 

Weight  of  feed-water  consumed 11 

Feed-water  consumed  per  hour 3 

Pressure  in  steam  pipe  above  atmosphere 

Vacuum  in  condenser 

Revolutions  per  minute 

Mean  effective  pressure  H.  P.  cylinder 

Mean  effective  pressure  L.  P.  cylinder 

Indicated  horse-power  H.  P.  cylinder 

Indicated  horse-power  L.  P.  cylinder 

Indicated  horse-power,  whole  engine 

Feed-water  consumed  per  I.  H.  P.  per  hour 

Measurements  based  on  Sample  Diagrams. 


Ordinary 

2.85 

hrs. 

,325 

Ibs. 

,973.7 

Ibs. 

120.6 

Ibs. 

27 

ins. 

195.3 

43.75 

Ibs. 

12.68 

Ibs. 

101.7 

H.P. 

118.9 

H.P. 

220.6 

H.P. 

18.01 

Ibs. 

H.  P. 
CYLINDER. 

L.  P. 
CYLINDER. 

Initial  pressure  above  atmosphere  . 
Cut-off  pressure  above  zero     .... 
Release  pressure  above  zero  .... 
Mean  effective  pressure 

Ibs. 
Ibs. 
Ibs. 
Ibs 

115.5 
104.9 
55.4 
43  1 

15 
20.6 
10.3 
12  69 

Back  pressure  at  mid  stroke,  above  or 
below  atmosphere  

Ibs 

+  23 

—  10  5 

Proportion  of  stroke  completed  at  cut-off 
Steam  accounted  for  at  cut-off    . 
Steam  accounted  for  at  release  . 
Proportion  of  feed-water  accounted  for 
at  cut-off 

Ibs. 
Ibs. 

.396 
11.33 
12.3 

629 

.387 
12.49 
12.49 

694 

Proportion  of  feed-water  accounted  for 
at  release       ...          .... 

683 

694 

155 


156  ENGINE    TESTS. 

Engine  No.  39  is  a  single  valve,  cross  compound,  unjacketed 
engine,  with  a  shaft  governor  operating  011  the  cut-off  of  the 
high-pressure  cylinder.  The  valves  are  of  the  piston  type  pro- 
vided with  an  inefficient  ring  packing.  A  jet  condenser  is 
used,  operated  by  an  independent  air-pump  driven  with  steam 
taken  from  the  engine  pipe.  The  quantity  thus  used  was 
determined  by  an  independent  test  and  allowed  for.  Steam  is 
supplied  from  vertical  water- tube  boilers,  and  a  separator  placed 
in  the  steam  pipe  secured  what  was  believed  to  be  commercially 
dry  steam  without  superheating.  The  valves  and  pistons  all 
leaked  a  considerable  amount.  The  load  consisted  of  dynamos 
furnishing  current  for  electric  lighting.  With  the  exception 
of  the  low-pressure  cylinder  and  the  valves,  this  engine  is 
the  same  as  No.  35.  During  the  interval  between  the  tests  the 
engine  had  been  provided  with  new  valves  fitted  with  packing 
and  a  complete  new  low-pressure  cylinder  of  larger  size. 

Referring  to  the  test  on  Engine  No.  35,  the  figures  given  here 
show  an  improvement,  due  largely  to  a  better  distribution  of 
the  steam,  which  was  accomplished  by  a  change  of  proportion 
in  the  steam  cylinders.  The  increase  in  the  size  of  the  low- 
pressure  cylinder  enabled  this  cylinder  to  do  a  larger  proportion 
of  the  work,  with  corresponding  advantage.  The  reduction 
in  the  quantity  of  feed  water  consumed  per  horse  power  per 
hour  amounted  to  18.3%  ;  and  the  reduction  in  the  steam 
accounted  for  by  the  diagrams  at  cut-off,  which  is  17.5%,  fur- 
nishes a  reason  for  the  change.  In  view  of  the  leakage  of  the 
valves  and  pistons,  it  is  not  surprising  that  the  proportion  of 
steam  accounted  for  is  low ;  and  this  is  true  in  the  case  of  both 
engines. 

To  make  a  ready  comparison  of  the  diagrams  in  the  two 
cases  under  consideration,  showing  the  general  effect  of  the 
change  of  cylinders,  diagrams  t'rom  Engine  No.  35,  taken  with 
the  same  load,  are  superposed  in  dotted  lines  upon  those  relat- 
ing to  No.  39,  which  are  represented  in  full  lines. 


120-n 

100- 
80- 
60- 
40- 
20- 

0- 
120- 

100- 

80- 
60- 
40- 
20- 
0- 


ENGINENo.  39 


H.P.  Head  End 


H.P.  Crank  End 


20- 


10- 


o- 


10- 


L.P.  Head  End 


L.P.  Crank  End 


-20 


-  10 


-   0 


-  10 


ENGINE    No.  40. 

Compound  Condensing  Engine. 


H.  P. 
CYLINDER. 

L.  P. 
CYLINDER 

Kind  of  engine 

Single 

valve 

Number  of  cylinders 

1 

1 

Diameter  of  cylinders      .          ins. 

18 

30 

Stroke  of  piston     ins. 

16 

1(3 

Clearance      % 

33 

9 

H.  P.  constant  for  1  Ib.  in.  e.  p.  one  rev- 

olution per  inin  H.P. 

.0103 

.0285 

Katio  of  areas  of  cylinders       

1 

2.78 

Condition  of  valves  and  pistons  regarding 

Practically 

Practically 

leakage  

tight 

tight 

Data  and  Results  of  Feed  -Water  Test. 

Character  of  steam 

Duration 

Weight  of  feed -water  consumed 

Feed-water  consumed  per  hour 

Pressure  in  steam  pipe  above  atmosphere 

Vacuum  in  condenser       

Revolutions  per  minute 

Mean  effective  pressure,  H.  P.  cylinder 

Mean  effective  pressure,  L.  P.  cylinder 

Indicated  horse-power,  H.  P.  cylinder 

Indicated  horse-power,  L.  P.  cylinder 

Indicated  horse-power,  whole  engine 

Feed-water  consumed  per  I.  H.  P.  per  hour 


Ordinary 


1.527 

hrs. 

9,660 

Ibs. 

6,326.1 

Ibs. 

126 

Ibs. 

21.1 

ins. 

228 

63.9 

Ibs. 

30.4 

Ibs. 

149.7 

H.P. 

197.9 

H.P. 

347.6 

H.P. 

18.2 

Ibs. 

Measurements  based  on  Sample  Diagrams. 


H.P. 
CYLINDER. 

L.  P. 
CYLINDER. 

Initial  pressure  above  atmosphere  .     .     Ibs. 

111.6 

49 

Cut-off  pressure  above  zero    ....     Ibs. 

114.8 

29.7 

Release  pressure  above  zero  ....     Ibs. 

82.4 

25.7 

Mean  effective  pressure     Ibs. 

63.4 

30.1 

Back  pressure  at  mid  stroke,  above  or 

below  atmosphere  Ibs. 

+  24.5 

(  . 

Proportion  of  stroke  completed  at  cut-off 

.595 

.795 

Steam  accounted  for  at  cut-off    .     .     .     Ibs. 

16.58 

17.58 

Steam  accounted  for  at  release    .     .     .     Ibs. 

15.59 

16.11 

Proportion  of  feed-water  accounted  for 

at  cut-off 

.911 

.965 

Proportion  of  feed-water  accounted  for 

at  release       

.857 

.885 

158 


159 

Engine  No.  40  is  a  vertical  single-acting  engine  with  unjack- 
eted  cylinders  and  a  single  piston  valve  fitted  with  ring  pack- 
ing, one  valve  serving  for  both  cylinders.  The  condensing 
apparatus  is  a  surface  condenser  with  air-pump  operated  by 
steam.  During  the  test  the  exhaust  from  the  air-pump  escaped 
to  the  atmosphere.  This  pump  was  of  insufficient  size  to  give 
a  proper  vacuum.  Steam  is  furnished  by  horizontal  return 
tubular  boilers.  It  was  found  by  calorimeter  test  that  at  a 
point  near  the  engine  it  contained  one-half  of  \°/0  of  moisture. 
The  pistons  and  the  valve  were  practically  tight,  although  in 
this  class  of  engines  there  is  always  some  escape  of  water  by 
the  piston  rings  into  the  crank  case.  The  load  consisted  of  a 
centrifugal  pump. 

The  feed- water  was  measured  by  collecting  the  water  dis- 
charged from  the  surface  condenser.  The  quantity  thus  deter- 
mined does  not  include  that  referred  to  above,  which  leaked 
from  the  steam  cylinders  into  the  crank  case,  and  which  there  is 
no  ready  means  of  determining. 

The  consumption  of  feed-water  here  given  was  less  than  the 
actual  amount  of  steam  which  passed  through  the  engine, 
owing  to  the  fact  above  noted  that  some  of  the  steam  which 
was  condensed  in  the  cylinders  passed  into  the  crank  case  and 
failed  to  be  measured.  This  accounts  for  the  large  proportions 
which  the  steam  accounted  for  at  cut-off  and  release  bears  to 
the  feed-water  consumption.  In  view  of  the  late  cut-off,  the 
high  back  pressure  in  the  small  cylinder,  the  excellent  quality 
of  the  steam  furnished  to  the  engine,  and  the  tightness  of  the 
valve,  all  of  which  tend  to  reduce  the  losses  shown  by  an 
analysis  of  the  diagram,  these  proportions  must  necessarily  be 
large.  The  leakage  referred  to  could  hardly  be  expected  to 
exceed  5%.  Assuming  it  to  be  5%,  the  feed- water  consump- 
tion would  stand  19.1  Ibs.,  and  the  proportions  of  steam  ac- 
counted for  at  cut-off  in  the  two  cylinders  .87  and  .92  respect- 
ively. 


ENGINE  No.  40 


H.P.  Cyl. 


-100 
-80 

•  60 
40 
20 

-  0 


L.P.  Cyl. 


-  40 


-  20 


ENGINE    No.  41. 


Compound  Condensing  Engine. 


H.  P. 
CYLINDER. 

L.  P. 

CYLINDER. 

Kind  of  engine     
Number  of  cylinders     
Diameter  of  cylinder 

ins. 
ins. 
ins. 

% 

H.P. 

ins. 
ins. 

Single 
1 

in 

2 
13 

7 

.00672 
1 
4 
5 
Considerable 
leakage 

valve 
1 
18i 
2 
13 
10 

.01755 
2.61 
5 

7 

Diameter  of  piston  rod       .     .     .     . 
Stroke  of  piston  
Clearance 

H.  P.  constant  for  one  Ib.  m.  e.  p.  one 
revolution  per  minute     .     .     .     . 
Ratio  of  areas  of  cylinders     .... 
Inside  diameter  of  steam  pipe 
Inside  diameter  of  exhaust  pipe 
Condition  of  valves  and  pistons  regard- 
ing leakage    

Data  and  Results  of  Feed -Water  Tests. 


TEST. 
CHARACTER  OF  LOAD. 

A. 
LIGHT  LOAD. 

B. 
HEAVY  LOAD. 

Character  of  steam  
Duration     hrs. 
Weight  of  feed-water  consumed.      .     .     Ibs. 
Eeed-water  consumed  per  hour  .     .     .     Ibs. 
Pressure   in   steam  pipe  above  atmos.     Ibs. 
Vacuum  in  condenser                                 ins 

Ordinary 
3.5 
7,203.5 

2,058 
129.7 
25  9 

Ordinary 
4.8 
18,043. 
3,759 
130.1 
25  5 

Revolutions  per  minute 

306 

298  5 

Mean  effective  pressure,  H.  P.  cylinder    Ibs. 
Mean  effective  pressure,  L.  P.  cylinder    Ibs. 
Indicated  horse-power,  H.  P.  cylinder   H.P. 
Indicated  horse-power,  L.  P.  cylinder   H.P. 
Indicated  horse-power,  whole  engine  .  H.P. 
Feed-water  consumed  per  I.  H.P.  per  hr.     Ibs. 

25.02 
7.27 
51.5 
39. 
90.5 
22.74 

48.5 
19 
97.3 
99.5 
196.8 
19.1 

Measurements  based  on  Sample  Diagrams,  heavy  load  Test. 


TEST. 

H.P. 
CYLINDER. 

L.  P. 
CYLINDER. 

Initial  pressure  above  atmosphere   .     .     Ibs. 
Corresponding  steam-pipe  or  receiver 
pressure   Ibs. 
Cut-off  pressure  above  zero    ....      Ibs. 
Release  pressure  above  zero  ....     Ibs. 
Mean  effective  pressure          .                     Ibs 

130 

132 
115.2 
63.1 

48  9 

20.3 

24.6  ' 
15. 

19  2 

Back  pressure  at  mid  stroke  above  or 
below  atmosphere       Ibs. 
Proportion  of  stroke  completed  at  cut-off 
Steam  accounted  for  at  cut-off    .     .     .     Ibs. 
Steam  accounted  for  at  release  .     .     .     Ibs. 
Proportion  of  feed-water  accounted  for 
at  cut-off 

+  20.3 
.382 
12.03 
13.43 

629 

—  11.1 
.409 
9.97 
12.76 

522 

Proportion  of  feed-w.  acc'd  for  at  release 

.703 

.668 

161 


162  ENGINE    TESTS. 

Engine  No.  41  is  a  vertical  cross-compound  unjacketed  high- 
speed engine,  having  unpacked  piston  valves,  one  for  each 
cylinder,  and  controlled  by  a  shaft  governor  operating  on  the 
cut-off  of  the  high-pressure  cylinder.  A  jet  condenser  is  used, 
operated  by  an  independent  air-pump  driven  by  steam  taken 
from  the  main  pipe.  The  quantity  of  steam  used  by  the  con- 
denser was  determined  by  an  independent  test  and  allowed  for. 
Allowance  was  also  made  for  steam  condensed  in  the  large  ser- 
vice main,  which  was  designed  for  supplying  several  other 
engines  besides  the  one  tested.  Steam  was  furnished  by  hori- 
zontal return  tubular  boilers,  and  a  calorimeter  test  showed  that 
it  contained  T%  of  1%  of  moisture.  The  valve  of  the  high- 
pressure  cylinder  was  found  to  leak  quite  badly.  That  of  the 
low-pressure  cylinder  was  reasonably  tight.  The  leakage  of 
the  valves  interfered  with  a  determination  of  the  condition  of 
the  pistons.  The  load  consisted  of  dynamos  furnishing  cur- 
rent for  electric  lighting.  The  tests  were  made  with  two  differ- 
ent loads,  other  conditions  remaining  the  same. 

If  the  results  of  this  test  are  compared  with  those  made  on 
a  four- valve  engine  such  as  No.  36,  which  showed  a  much  more 
economical  performance,  the  effect  of  various  features  in  the 
design  of  the  engine  are  apparent.  Engine  No.  41  had  a  single 
valve,  which  secured  less  perfect  distribution  of  steam  than  the 
four  valves  of  the  other  engine.  It  had  larger  percentages  of 
clearance  space,  and  finally,  the  type  of  valve  used  permitted  a 
much  larger  amount  of  leakage  than  occurred  in  the  other 
engine.  Engine  No.  41,  however,  had  the  advantage  of  more 
rapid  reciprocations  ;  but  this,  it  appears,  did  not  have  sufficient 
effect  to  overcome  the  losses  due  to  the  causes  mentioned. 


ENGINE  No.  41a 


I20-, 
100- 
80- 
60- 
40- 
20- 

o- 


100- 
80- 
60- 
40- 
20- 

o- 


H.P.  Top 


L.P.  Top 


L.P.  Bottom 


ENGINE  No.41b 


120^ 

100- 

80- 

60- 

40- 

20- 

0- 

120  — 

100- 

80— 

60- 

40 

20- 

0- 


H.P.  Top 


H-P.  Bottom 


20- 
10- 
0— 
10- 

20- 
10- 

O- 
10- 


L.P.Top 


L.P.  Bottom 


ENGINE    No.  42. 

Compound  Non-Condensing  Engine. 


H.P. 

CYLINDER. 

L.P. 

CYLINDER. 

Kind  of  engine       

Single  valve 

Number  of  cylinders  .     .     .     . 

I 

1 

Diameter  of  cylinders      ....     ins. 

1H 

182 

Diameter  of  piston  rod    .     .     .     .     ins. 

2 

2 

Stroke  of  piston     ins. 

13 

13 

Clearance      .         % 

7 

10 

H.  P.  Constant  for  one  Ib.  m.  e.  p. 

one  rev.  per  min  H.P. 

.00672 

.01755 

Ratio  of  areas  of  cylinders  .... 

1 

2.61 

Condition  of   valves  and    pistons 

Considerable 

regarding  leakage     .... 

leakage 

Data  and  Results  of  Feed  -  Water  Tests. 


TEST. 
CONDITIONS  REGARDING  LOAD. 

A. 

LIGHT  LOAD. 

B. 
HEAVY  LOAD. 

Character  of  steam     ...  ^    .     .     . 

Ordinary 

Ordinary 

Duration       .     .     .     .     ...     .    hrs. 

5 

5 

Weight  of  feed-water  consumed    .    Ibs. 

10,228 

15,369 

Feed-water  consumed  per  hour     .    Ibs. 

2,045.6 

3,842.2 

Press,  in  steam  pipe  above  atmos.    Ibs. 

126.5 

128 

Revolutions  per  minute  .... 

300.2 

292.7 

Mean  effective  pressure,  H.P.  cyl.    Ibs. 

20.36 

42.16 

Mean  effective  pressure,  L.P.  cyl.    Ibs. 

.86 

13.56 

Indicated  horse-power,  H.  P.  cyl.  H.P. 

41.05 

82.89 

Indicated  horse-power,  L.  P.  cyl.  H.P. 

4.53 

69.59 

Indicated  H.  P.,  whole  engine      .  H.P. 

45.58 

152.48 

Feed-water  cons,  per  I.  H.P.  per  hr.    Ibs. 

44.89 

25.2 

Measurements  based  on  Sample  Diagrams. 


TEST. 
CONDITIONS  REGARDING  LOAD. 

H.P.  CYL. 

L.P.  CYL. 

H.P.CYL. 

L.P.  CYL. 

Initial  pressure  above  atmosphere    Ibs. 

116.4 

10.3 

120 

30 

Corresponding  steam-pipe  or  re- 

ceiver pressure    Ibs. 

125. 

128. 

Cut-off  pressure  above  zero     .     .     Ibs. 

112.4 

19.5 

120.3 

53.5 

Release  pressure  above  zero     .     .     Ibs. 

40  9 

64.7 

20.6 

Mean  effective  pressure       .     .     .     Ibs. 

20.2 

.7 

42.27 

14.1 

Backpressure  atniid  stroke  above 

atmosphere    Ibs. 

10.7 

1. 

29.9 

1.8 

Proportion     of   stroke  completed 

at  cut-off              

.107 

.526 

.389 

.424 

Steam  accounted  for  at  cut-off     .     Ibs. 

10.21 

28.26 

15.56 

13.82 

Steam  accounted  for  at  release    .     Ibs. 

26.43 

17.16 

16.66 

Proportion  of  feed-water  account- 

ed for  at  cut-off     .... 

.228 

.629 

.617 

.548 

Proportion  of  feed-water  account- 

ed for  at   release    .     .     .    v 

.589 

.681 

.661 

165 


166  ENGINE    TESTS. 

Engine  No.  42  is  of  the  vertical  cross-compound  un jacketed 
high-speed  class.  It  is  a  duplicate  of  Engine  No.  41,  being 
located  in  the  same  power  house,  and  forming  a  part  of  the 
same  plant.  It  was  supplied  with  steam  from  a  different  por- 
tion of  the  service  main,  the  water  condensed  in  which  returned 
back  to  the  boiler.  Unlike  engine  No.  41  it  was  run  non-con- 
densing. The  valves  and  pistons  leaked  to  about  the  same 
extent  as  in  the  other  engine,  and  the  load  was  of  the  same 
character.  The  tests  were  two  in  number,  one  being  made 
with  a  very  light  load. 

These  tests  bring  out  very  forcibly  the  wastefulness  of  a  non- 
condensing  compound  engine  of  this  type  when  carrying  an 
extremely  light  load.  In  the  case  of  the  first  test  the  load  was 
so  small  that  the  low-pressure  cylinder  contributed  only  about 
10%  of  the  whole  power,  which  is  so  small  as  to  be  immaterial ; 
and  consequently,  the  engine  showed  simply  the  economy  due 
to  a  non-condensing  cylinder  of  this  type  carrying  a  high  back 
pressure,  and  working  at  a  comparatively  early  cut-off.  The 
effect  of  valve  leakage  is  revealed  by  the  small  proportion  of 
steam  accounted  for  by  the  indicator.  Compared  with  the  con- 
densing engine  of  the  same  type,  No.  41,  there  is  a  marked 
advantage  due  to  the  use  of  the  condenser ;  and  this  appears  to 
be  especially  true  in  the  case  of  the  light  load.  Comparing  the 
two  heavy-load  tests  the  reduced  consumption  of  feed-water  is 
6.1  Ibs.  per  I.  H.  P.  per  hour,  or  about  24%.  In  the  light-load 
test  there  is  a  remarkable  increase  in  the  steam  accounted  for 
at  release  of  the  high-pressure  cylinder  over  that  shown  at  cut- 
off. It  is  due  largely  no  doubt  to  valve  leakage. 


ENGINE  No.  42a 


H.P.  Top 


H.P.  Bottom 


120 
-100 
-80 

—  60 
-40 
-20 

-  0 
120 

-100 

-  80 

—  60 
40 

-20 

-  0 


L.P.  Top 


-30 
-20 

—  10 

—  0 


L.P.  Bottom 


—20 
-  10 

0 


ENGINE  No.42b 


H.P.  Top 


H.P.  Bottom 


-120 
-100 
-80 

-  60 
-40 
-20 

-  0 
-120 
-100 
-80 
-60 
-40 
-20 

-  0 


L.P.  Top 


L.P.  Bottom 


30 

20 

10 

0 


ENGINE    No.   43. 

Compound  Condensing  Engine. 


H.P.  CYLINDER. 

L.P.  CYLINDER. 

Kind  of  engine    
Number  of  cylinders 

Four  valve 
1 

27.9 
5 
5 
2.5 

.1828 
1 
12 

Fairly  tight 

(Corliss) 
1 
48.3 
6 
5 
2.5 

.556 
3.04 

Fairly  tight 

Diameter  of  cylinder                         .     .     ins. 

Diameter  of  piston  rod      ins. 
Stroke  of  piston                  ft. 

Clearance   (assumed)    % 
H.  P.  constant  for  one  Ib.  m.  e.  p.  one 
rev.  per  min  H.P. 
Ratio  of  areas  of  cylinders     .     .     .     . 
Inside  diameter  of  steam  pipe     .     .     .     ins. 
Condition  of  valves  and  pistons  regard- 
in0"  leakage              

Data  and  Results  of  Feed  -  Water  Test. 

Character  of  steam Superh'd  44. 

Duration V   •,  • 19-08 

Weight  of  feed-water  consumed 257,351 

Feed-water  consumed  per  hour 13,488 


Pressure  in  steam  pipe  above  atmosphere 
Pressure  in  receiver  above  atmosphere  . 

Vacuum  in  condenser     .          

Revolutions  per  minute 

Mean  effective  pressure  H.  P.  cylinder  .  . 
Mean  effective  pressure  L.  P.  cylinder  .  . 
Indicated  horse-power  H.  P.  cylinder  .  . 
Indicated  horse-power  L.  P.  cylinder  .  . 
Indicated  horse-power,  whole  engine  .  . 
Feed-water  consumed  per  I.  H.  P.  per  hour 


119.8 
11.0 
25.7 
70.03 
39.04 
13.28 
499.9 
517.2 
1,017.1 
13.26 


5  degs. 
hrs. 
Ibs. 
Ibs. 
Ibs. 
Ibs. 
ins. 


Ibs.. 
H.P. 
H.P. 
H.P. 
Ibs. 


Measurements  Based  on  Sample  Diagrams. 


H.  P. 

CYLINDER. 

L.P. 
CYLINDER. 

Initial  pressure  above  atmosphere     .     .     . 

Ibs. 

109 

12.9 

Corresponding  steam-pipe  or  receiver  press. 

Ibs. 

113 

Cut-off  pressure  above  zero      

Ibs. 

114.8 

22.1 

Release  pressure  above  zero     

Ibs. 

31.4 

7.4 

Mean  effective  pressure  .     

Ibs. 

40.03 

13.21 

Back  pressure  at  mid  stroke,  above  or  be- 

low atmosphere  

Ibs. 

+  16. 

-12.2 

Proportion  of  stroke  completed  at  cut-off  . 

.236 

.312 

Steam  accounted  for  at  cut-off      .... 

Ibs. 

10.1 

9.39 

Steam  accounted  for  at  release     .... 

Ibs. 

12.0 

10.21 

Proportion  of  feed-water  accounted  for  at 

cut-off    

.762 

.708 

Proportion  of  feed-water  accounted  for  at 

release 

.908 

.77 

169 


170  ENGINE    TESTS. 

Engine  No.  43  is  a  horizontal  cross  compound  with  jacketed 
cylinders  and  unjacketed  receiver.  It  exhausts  into  a  jet  con- 
denser provided  with  a  direct  connected  air-pump.  The  jacket 
space  of  either  cylinder,  which  is  confined  to  the  barrel  of  the 
cylinder,  forms  a  thoroughfare  through  which  the  steam  passes 
to  the  top  chest,  the  steam  entering  at  the  bottom.  The  spaces 
are  drained  by  traps.  Steam  is  supplied  by  vertical  boilers 
which  superheat.  The  valves  and  pistons  of  the  H.  P.  cylin- 
der leaked  a  small  amount,  but  those  of  the  L.  P.  cylinder  were 
practically  tight.  The  load  consisted  of  cotton  machinery. 

The  test  reported  is  the  collective  result  of  four  indepen- 
dent trials  of  4.5  to  5  hours  each. 

A  noticeable  feature  in  these  results  is  the  increase  in  the 
steam  accounted  for  at  release  H.  P.  cylinder  over  that  shown 
at  cut-off,  viz.,  .146.  In  working  out  these  figures  the  clear- 
ance was  assumed  at  2-J-  %.  If  the  clearance  were  in  reality 
1  %  more  (i.  e.,  3.5  %)  the  increase  is  reduced  to  .123.  Even 
this  is  notable. 


ENGINE  No.  43 


H.P.  Head  End 


100 
80 
60 
40 
20 
0 


H.P.  Crank  End 


100 
80 
60 
40 
20 
-  0 


L.P.  Head  End 


L.P.  Crank  End 


15 
10 
5 
0 
6 
10 

15 
10 

6' 
0 


L-  10 


ENGINE   No.  44. 


Compound  Non-Condensing  Engine. 


H.P. 

CYLINDER. 

L.  P. 

CYLINDER. 

Kind  of  engine     
Number  of  cylinders 

Single 
1 

valve 
1 

Diameter  of  cylinder     .     ...     .     .     ins. 
Stroke  of  piston  ft. 
Clearance   % 

11 
11 
33 

19 
11 
9 

H.  P.  constant  for  1  Ib.  m.  e.  p.  one 
revolution  per  minute    ....  H.P. 
Ratio  of  areas  of  cylinders     .... 
Inside  diameter  of  steam  pipe     .     .     .     ins. 
Condition  of  valves  and  pistons  regard- 
in0"  leakage                        .... 

.00264 
1 
5 

Practically 
ti°'ht 

.00788 
2.98 

Practically 
tio-ht 

Data  and  Results  of  Feed-  Water  Test. 


Character  of  steam    .     .     .     .     .     .     .     .     . 

Duration ....•-.. 

Weight  of  feed-water  consumed  .  .  .  .  . 
Feed-water  consumed  per  hour  ..... 
Pressure  in  steam  pipe  above  atmosphere  .  . 

Revolutions  per  minute 

Mean  effective  pressure,  H.  P.  cylinder  .  . 
Mean  effective  pressure,  L.  P.  cylinder  .  . 
Indicated  horse-power,  H.  P.  cylinder  .  . 
Indicated  horse-power,  L.  P.  cylinder  .  .  , 
Indicated  horse- power,  whole  engine  .  .  . 
Feed-water  consumed  per  I.  H.  P.  per  hour  . 


Ordinary 


5.33 

hrs. 

13,397 

Ibs. 

2,511.8 

Ibs. 

135.9 

Ibs. 

296.3 

67.2 

Ibs. 

23.3 

Ibs. 

53.6 

H.P. 

56 

H.P. 

109.66 

H.P. 

22.91 

Ibs. 

Measurements  based  on  Sample  Diagrams. 


H.P. 
CYLINDER. 

L.  P. 
CYLINDER. 

Initial  pressure  above  atmosphere   .     , 
Corresponding  steam-pipe  pressure 
Cut-off  pressure  above  zero    .     .     .1 
Release  pressure  above  zero  .     .     '.'     . 
Mean  effective  pressure              •            . 

Ibs. 
Ibs. 
Ibs. 
Ibs. 
Ibs. 

130 
132 
128.2 
89.5 
67.1 

55 

35.5 

28.4 
23  6 

Back  pressure  at  lowest  point  above 
atmosphere   
Proportion  of  stroke  completed  at  cut- 
off                             

Ibs. 

30 
.605 

0 
.662 

Steam  accounted  for  at  cut-off    .     .     . 
Steam  accounted  for  at  release    .     .     . 
Proportion  of  feed-  water  accounted  for 
at  cut-off                       

Ibs. 
Ibs. 

18.39 
18.56 

.803 

14.96 
16.61 

.653 

Proportion  of  feed-water  accounted  for 
at  release       

.81 

.725 

172 


ENGINE  No.   44. 


173 


Engine  No.  44  is  a  vertical  cross-compound,  single-acting, 
un  jacketed,  high-speed  engine,  having  a  single  piston  valve 
fitted  with  ring  packing,  the  speed  being  controlled  by  a  shaft 
governor.  Steam  is  supplied  by  a  horizontal  return  tubular 
boiler,  which  by  calorimeter  test  contained  some  2%  of  moist- 
ture.  Drip  pockets  in  the  main  pipe  and  at  the  throttle  valve, 
which  were  trapped,  intercepted  most  of  the  entrained  water 
which  would  otherwise  have  passed  into  the  engine.  The  load 
consisted  of  an  electric  generator  with  constant  output.  The 
valve  and  pistons  were  very  nearly  tight. 


120- 
100- 
80 
60- 
40- 
20- 
0- 


L.P.  Cyl. 


-60 


-40 


-20 


-    0 


ENGINE    No.  45. 

Compound  Condensing  Engine. 


H.  P.  CYMNDEB. 

L.  P.  CYLIXDER. 

Kind  of  engine 

Doubl 
1 
14 
21 
24 
3.6 

.01839 
1 

Consider  a" 

3  valve 
1 
28 
21 
24 
6.4 

.07436 
4.04 

Die  leakage 

Number  of  cylinders     .     .     .     .     . 
Diameter  of  cylinder     ins. 

Diameter  of  piston  rod       ins 

Stroke  of  piston  .     ,~   ins. 
Clearance   '    .         % 
H.P.  constant  for  one  Ib.  m.e.p.  one 
revolution  per  minute      .     .     .     .H.P. 
Ratio  of  areas  of  cylinders     .... 
Condition  of  valves  and  pistons  regard- 
ing leakage    

Data  and  Results  of  Feed  -  Water  Tests. 


TEST. 

A. 

B. 

C. 

Character  of  steam  '. 
Duration                                                         hrs 

Ordinary 
4 

Ordinary 
4 

Ordinary 
3 

Weight  of  feed-water  consumed  .  .  Ibs. 
Feed-water  consumed  per  hour  .  .  .  Ibs. 
Pressure  in  steam  -pipe  above  atmos.  .  Ibs. 
Pressure  in  receiver  Ibs 

19,014 
4,753.7 
119.9 
10  1 

15,366 
3,841.6 
120.4 
4  5 

6,375 
2,125 
117.6 

Vacuum  in  condenser  ins 

25  1 

25  5 

25  6 

Revolutions  per  minute 

161  75 

162  75 

170  1 

Mean  effective  pressure,  H.  P.  cylinder     Ibs. 
Mean  effective  pressure,  L.  P.  cylinder     Ibs. 
Indicated  horse-power,  H.  P.  cylinder  H.P. 
Indicated  horse-power,  L.  P.  cylinder    H.P. 
Indicated  horse-power,  whole  engine  .  H.P. 
Feed-water  consumed  per  I.  H.  P.  per 
hour     ""....     Ibs. 

57.4 
10.39 
170.74 
124.97 

295.71 

16.07 

49.97 
7.85 
149.55 
95 
244.55 

15.71 

25.89 
8.35 
80.98 
42.41 
123.39 

17.22 

Measurements  based  on  Sample  Diagrams. 


TEST. 

A 

. 

C 

Initial  pressure  above  atmosphere   .     .     Ibs. 
Corresponding  steam-pipe  or  receiver 
pressure                   Ibs 

H.P. 
117.4 

120 

L.P. 
9.5 

10  5 

H.P. 

118 

119 

L.P. 

5.1 

Cut-off  pressure  above  zero    ....     Ibs. 
Release  pressure  above  zero  ....     Ibs. 
Mean  effective  pressure      Ibs. 
Back  pressure  at  mid  stroke  above  or 
below  atmospere                    .     .          Ibs 

114.5 
42.5 
57.95 

+10  9 

18.6 

7.7 
10.37 

—11  6 

121.8 
14.1 
24.97 

—  36 

7.5 
3.7 
3.47 

—12  4 

Proportion  of  stroke  completed  at  cut- 
off              

.336 

.338 

044 

336 

Steam  accounted  for  at  cut-off    .     .     .     Ibs. 
Steam  accounted  for  at  release  .     .     .     Ibs. 
Proportion  of  feed-water  accounted  for 
at  cut-off       

12.08 
12.75 

751 

9.06 
10.69 

563 

6.21 
11.32 

361 

8.67 
12.82 

503 

Proportion  of  feed-water  accounted  for 
at  release       

.793 

.665 

.657 

.744 

174 


ENGINE  No.  45. 


175 


ENGINE    No.  45    (Continued), 
Data  and  Results  of  Feed-Water  Tests. 


TEST. 

D. 

E.    . 
NON- 
CONDENSING. 

Character  of  steam  

Ordinary 
3 
13,356.5 
4,45^.2 
118.9 
14.1 
25.8 
164.77 
46.94 
10.99 
142.23 
134.65 
276.88 
16.07 

Ordinary 
3 
18,614 
6,204.7 
118 
27.8 

165.66 
52.4 
8.81 
158.54 
108.47 
267.1 
23.24 

Duration  .  hrs. 

Weight  of  feed-water  consumed  .  .  Ibs. 
Feed-water  consumed  per  hour  .  .  .  Ibs. 
Pressure  in  steam  pipe  above  atmos.  Ibs. 
Pressure  in  receiver  above  atmosphere  Ibs. 
Vacuum  in  condenser  .  ins 

Revolutions  per  minute 

Mean  effective  pressure,  H.  P.  cylinder  Ibs. 
Mean  effective  pressure,  L.  P.  cylinder  Ibs. 
Indicated  horse-power,  H.  P.  cylinder  H.P. 
Indicated  horse-power,  L.  P.  cylinder  H.P. 
Indicated  horse-power,  whole  engine  .  H.P. 
Feed-water  consumed  per  I.  H.P.  per  hr.  Ibs. 

Measurements  based  on  Sample  Diagrams. 


TEST. 

D. 
CONDENSING. 

E. 

NON- 
CONDENSING. 

Initial  pressure  above  atmosphere  .     .     Ibs. 
Corresponding  steam-pipe  or  receiver 
pressure    
Cut-off  pressure  above  zero    ....     Ibs. 
Release  pressure  above  zero  ....     Ibs. 
Mean  effective  pressure      Ibs. 
Back  pressure  at  mid  stroke  above  or 
below  atmosphere                  .     .     .     Ibs. 

H.P.CY. 

117.6 

118 
113.1 
38.3 
47.65 

+16. 

.3 
11.16 
12.06 

.694 

.750 

L.P.  CY. 
14.1 

14.5 
22.2 
7.0 
11.07 

-12.2 

.239 
8.82 
10.71 

.548 
.666 

H.P.CY. 
113.1 

115 
110.8 
58.2 
50.94 

+28.7 

.487 
18.46 
19.1 

.794 

.821 

L.P.  CY. 

27.8 

28.5 
31.9 
14.9 

8.77 

+1.2 

.406 
15.83 
18.3 

.681 

.787 

Proportion  of  stroke  completed  at  cut- 
off                            

Steam  accounted  for  at  cut-off    .     .     .     Ibs. 
Steam  accounted  for  at  release  .     .     .     Ibs. 
Proportion  of  feed-water  accounted  for 
at  cut-off       
Proportion  of  feed-water  accounted  for 
at  release 

Engine  No.  45  is  a  horizontal  cross-compound  with  unjack- 
eted  cylinders  and  unjacketed  receiver.  There  is  a  shaft  gov- 
ernor operating  on  the  cut-off  of  the  H.  P.  cylinder.  The 
main  valves  are  balanced  slides.  The  cut-off  valve  rides  on  a 
seat  in  the  interior  of  the  main  valve,  which  is  of  box  pattern. 
The  engine  exhausts  into  a  surface  condenser,  with  indepen- 
dent air-pumps,  the  latter  exhausting  to  waste.  The  feed-water 


176  ENGINE    TESTS. 

consumption  was  found  by  weighing  the  water  discharged  by 
the  air-pump.  Steam  was  drawn  from  the  main  service  of  a 
large  plant,  and  a  calorimeter  test  showed  that  it  was  practically 
dry.  The  main  valve  of  the  H.  P.  cylinder  leaked  quite  badly. 
The  other  valves  and  pistons  leaked  a  small  amount.  The 
engine  supplied  power  to  dynamos  for  electric  lighting.  A 
series  of  tests  was  made  with  different  loads,  and  in  one  case 
the  engine  was  run  non-condensing. 

Considering  the  wide  changes  of  load  in  the  tests  A,  B,  and 
C,  viz.,  from  295.  H.  P.  to  123.  H.  P.,  the  small  difference  in 
economy,  15.71  to  17.22,  is  noteworthy.  Probably  the  leakage 
of  the  valves  of  the  H.  P.  cylinder  affected  the  matter,  but  to 
what  extent  can  only  be  conjectured.  The  economy  is  at  best 
much  below  that  obtained  from  some  of  the  four- valve  engines, 
and  excessive  leakage  is  the  only  thing  which  satisfactorily 
explains  it.  The  results  of  tests  D  and  E,  condensing  and 
non-condensing,  are  respectively  16.07  Ibs.  and  23.24  Ibs.,  from 
which  it  appears  that  the  consumption  when  running  condens- 
ing was  30.9%  less  than  when  running  non-condensing. 


ENGINE  No.  45a 


H. P.  Head  End 


H.P.  Crank  End 


120 

100 

80 

60 

40 

20 

0 

120 
100 
80 
60 
40 
20 
0 


L.P.  Head  End 


L.P.  Crank  End 


ENGINE  No.  45c 


H.P.  Head  End 


H.P.  Crank  End 


-120 
-100 

-  80 

-  60 
-40 
-20 

—    0 
-120 

100 
-80 
.  60 

-  40 

-  20 

-  0 


L.P.  Head  End 


L.P.  Crank  End 


o 

5 
10 
15 


ENGINE  No.  45d 


H.P.  Head  End 


H. P.  Crank  End 


120 
-IOO 
-8O 
-6O 
-40 
-20 

-  0 
-120 

-100 
-80 
-60 
-4O 
-20 
-  O 


L  P.  Head  End 


15 
10 
5 
O 

5 

10 

15 
IO 
5 
O 
5 
10 


ENGINE  No.4-5e 


H.P.  Head  End 


H.P.  Crank  End 


-120 
-100 
-80 
-60 
-4O 

-20 
-  0 
-120 
-100 
-80 
-60 
-40 

-20 
L-  0 


L.P.  Head  End 


-30 


-20 


-  10 


-  0 


ENGINE    No.  46. 

Compound  Non-Condensing  Engine. 


H.P. 
CYLINDER. 

L.  P. 
CYLINDER. 

Kind  of  engine       .     .     .     ... 

Four  valve 

Number  of  cylinders  

I 

1       i 

Diameter  of  cylinders      .     ...  . 

ins. 

17.5 

28 

Diameter  of  piston  rod    .     .     .  .'. 

ins. 

31 

31 

Stroke  of  piston     .     .,..=';     .     • 

ins. 

48 

48 

Clearance      

% 

4.1 

5.8 

H.  P.  Constant  for  one  Ib.  in.  e.  p. 

one  rev.  per  min  

H.P 

.0572 

.148 

Ratio  of  areas  of  cylinders  . 

1 

2.587 

Inside  diameter  of  steam  pipe  . 

ins. 

7 

Inside  diameter  of  exhaust  pipe    . 

ins. 

8 

12 

Condition  of   valves  and    pistons 

regarding  leakage     .... 

Practically  tight 

Data  and  Results  of  Feed -Water  Tests. 


TEST. 

A. 

B. 

Character  of  steam     .     .     . 

Ordinary 

Ordinary 

Duration       .     .     ,     .  ,    .     .     .     .    hrs. 

8.55 

7.87 

Weight  of  feed-water  consumed   .    Ibs. 

65,591 

82,697 

Feed-water  consumed  per  hour     .    Ibs. 

7,671.2 

10,507.9 

Press,  in  steam  pipe  above  atmos.    Ibs. 

128.7 

135.5 

Pressure  in  receiver  above  atmos. 

27.2 

29.5 

Revolutions  per  minute  .... 

101.02 

99.06 

Mean  effective  pressure,  H.P.  cyl.    Ibs. 

34.83 

52.42 

Mean  effective  pressure,  L.P.  cyl.    Ibs. 

9.75 

14.19 

Indicated  horse-power,  H.  P.  cyl.  H.P. 

201.3 

278.84 

Indicated  horse-power,  L.  P.  cyl.  H.P. 

145.6 

207.85 

Indicated  H.  P.,  whole  engine      .  H.P. 

346.9 

486  69 

Feed-water  cons,  per  I.  H.  P.  per  hr.    Ibs. 

22.11 

21.59 

Measurements  based  on  Sample  Diagrams. 


H.P.CYL. 

L.P.  CYL. 

H.'P.CYL. 

L.P.  CYL. 

Initial  pressure  above  atmosphere    Ibs. 
Corresponding    steam-pipe    pres- 
sure                            Ibs 

118.8 

129  2 

28.01 

125.3 
136 

30.3 

Cut-off  pressure  above  zero     .     .     Ibs. 
Release  pressure  above  zero     .     .     Ibs. 
Mean  effective  pressure       .     .     .     Ibs. 
Back  pressure  at  mid  stroke  above 
atmosphere                                    Ibs 

112.37 
3981 
34.66 

32  0 

34.31 

13.88 
9.66 

2  2 

116.52 
51.76 
49.03 

34  3 

34.91 
18.26 
14.22 

2  9 

Proportion     of   stroke  completed 
at  cut-off 

309 

338 

419 

474 

Steam  accounted  for  at  cut-off     .     Ibs. 
Steam  accounted  for  at  release    .     Ibs. 
Proportion  of  feed-water  account- 
ed for  at  cut-off     .... 
Proportion  of  feed-water  account- 
ed for  at   release    .... 

17.83 
20.34 

.806 
.919 

15.81 
18.61 

.715 
.842 

17.62 
18.43 

.816 
.854 

16.03 
17.54 

.743 
.813 

181 


182  ENGINE    TESTS. 

Engine  No.  46  is  a  cross-compound,  with  horizontal  unjack- 
eted  cylinders  and  unjacketed  receiver.  The  valves  are  all 
plain  slides.  The  steam  was  drawn  from  horizontal  water-tube 
boilers,  and  contained  0.7  %  of  moisture  by  calorimeter  test. 
The  load  was  miscellaneous  iron-working  machinery.  Tests 
were  made  with  two  different  loads.  The  valves  and  pistons 
were  all  in  excellent  condition  as  regards  leakage. 

It  is  evident  from  an  analysis  of  the  diagrams  in  these  tests, 
that  the  economy  was  as  high  as  could  be  expected  under  the 
conditions  of  boiler  pressure,  ratio  of  cylinder  areas,  and  cut- 
off. For  higher  economy  a  higher  pressure,  larger  ratio  of 
cylinder  area,  and  earlier  cut-off  are  required.  It  must  be 
noted,  however,  that  the  distribution  is  not  the  most  perfect, 
and  there  is  rather  a  high  back  pressure  in  the  L.  P.  cylinder. 


ENGINE  No.  46a 


H.P.  Head  End 


H.P.  Crank  End 


-120 
-100 
-80 
-60 
-40 
-20 

-  0 

-120 
-100 
-80 

-60 
40 

-20 

-  0 


30- 

20- 

10- 

0- 

30-i 

20- 

10- 

0- 


L.P.  Head  End 


L.P.  Crank  End 


ENGINE  No.  46b 


H.P.  Head  End 


H. P.  Crank  End 


1—120 


-  80 


-  40 


L.    0 


M20 


-  80 


-  40 


L    0 


30- 

20- 

10- 


L.P.  Head  End 


30- 

20- 

10- 

0- 


L.P.  Crank  End 


ENGINE   No.   47. 

Compound  Condensing  Engine. 


H.P.  CYLINDER. 

L.P.  CYLINDER. 

Kind,  of  en°ine 

Four  valve 

Number  of  cylinders                .     ... 

1                            1 

Diameter  of  cylinder          .  ~  . 

ins. 

183V 

44is 

Diameter  of  piston  rod      .     .... 

ins. 

Hi* 

4i'5 

Stroke  of  piston  ........ 

ft. 

6 

0 

Clearance   

% 

2.3 

1.8 

H.  P.  constant  for  one  Ib.  m.  e.  p.  one 

rev.  per  min  

H.P. 

.08728 

.5584 

Ratio  of  areas  of  cylinders     .     ... 

1 

6.398 

Inside  diameter  of  steam  pipe     .     »     . 

ins. 

8 

14 

Inside  diameter  of  exhaust  pipe      ,     . 

ins. 

9 

16 

Condition  of  valves  and  pistons  regard- 

Practically 

Considerable 

ing  leakage   

tight 

leakage 

Data  and  Results  of  Feed -Water  Tests. 


TEST. 
CONDITIONS  REGARDING  USE  OF  JACKETS. 

A. 
JACKETS 

OFF. 

B. 
JACKETS 

ON. 

c. 

JACKETS 

ON. 

D. 
JACKETS 

ON. 

Character  of  steam  .     .-'«..-.     . 
Duration    hrs. 
Weight  of  dry  steam  consumed  .     Ibs. 
Dry  steam  consumed  per  hour  .     Ibs. 
Pressure    in   steam  pipe   above 
atmosphere    Ibs 

4.817 
42,147. 

8,749.8 

150.7 

10.6 
27. 
60.31 

67.79 
9.87 
366.8 
332.52 
689.32 
12.69 

Ordina 
4.833 
42,643. 

8,823.3 

151.1 

9.4 
27.3 
60.54 

66.15 
10.63 
349.52 
359.31 
708.33 
12.45 

ry 

8,596.6 
150.5 

15.0 
27.1 
60.59 

59.9 
10.78 
316.77 
364.69 
681.45 
12.61 

8,707. 
151.4 

19.4 
28.0 
60.33 

57.13 
11.39 
300.85 
383.71 
684.56 
12.72 

Pressure     in     receiver     above 
atmosphere    .     .     .     ...     Ibs. 
Vacuum  in  condenser  ....     ins. 
Revolutions  per  minute    . 
Mean  effective  pressure,  H.  P. 
cylinder    Ibs. 
Mean  effective  pressure,  L.  P. 
cylinder                                        Ibs 

Indicated    horse-power,    H.    P. 
cylinder     .H.P. 
Indicated     horse-power,    L.    P. 
cylinder   H.P. 
Indicated    horse-power,     whole 
engine  H.P. 
Dry  steam  consumed  per  I.  H.P. 
per  hr                                           Ibs 

185 


186 


ENGINE    TESTS. 


Measurements  Based  on  Samnle  Diaarams.     Engine  No.  47. 


TEST. 

^. 

I 

j. 

H.P.CYL. 

L.P.  CYL. 

H.P.CYL. 

L.P.CYL. 

Initial  pressure  above  atmosphere  Ibs. 

145.2 

9.8 

146.1 

9. 

Corresponding  steam-pipe  or  re- 

ceiver pressure  ....          Ibs. 

150. 

10.6 

149.2 

95 

Cut-off  pressure  above  zero   .          Ibs. 

149.2 

20. 

149.3 

18.9 

Release  pressure  above  zero  .          Ibs. 

42.5 

5.3 

41. 

5.4 

Mean  effective  pressure     .     .          Ibs. 

68.19 

9.78 

66.06 

10.55 

Back   pressure   at    mid   stroke 

above  or  below  atmosphere       Ibs. 

+10.9 

-12.1 

+10.1 

-12.6 

Proportion  of  stroke  completes 

at  cut-off 

.281 

25 

.263 

.282 

Steam  accounted  for  at  cut-off       Ibs. 

10.00 

8.69 

9.22 

9.13 

Steam  accounted  for  at  release       Ibs. 

10.34 

9.54 

9.59 

9.61 

Proportion    of    feed-water    ac- 

counted for  at  cut-off  . 

.788 

.685 

.740 

.733 

Proportion    of     feed-water    ac- 

counted for  at  release      .     . 

.815 

.752 

.770 

.771 

Engine  No.  47  is  a  horizontal  tandem  compound,  with 
jacketed  cylinders  and  a  reheater.  The  condenser  is  of  the 
siphon  type  with  water  supplied  by  gravity.  The  jacketing 
applies  to  heads  and  barrel  of  the  H.  P.  cylinder,  and  to  the 
heads  but  not  the  barrel  of  the  L.  P.  cylinder.  The  reheater  is 
of  the  tubular  type,  and  contains  a  sufficient  area  of  surface  to 
superheat  the  steam  passing  to  the  L.  P.  cylinder,  although 
some  of  that  entering  the  heater  remains  in  a  condensed 
state,  and  is  drawn  off  by  a  trap.  The  valves  are  all  of  the 
gridiron  type.  The  steam  is  furnished  by  horizontal  tubular 
boilers,  and  it  was  found  by  calorimeter  test  to  be  practically 
dry.  The  valves  and  piston  of  the  H.  P.  cylinder  were  found 
in  good  condition.  The  steam  valve  at  the  head  end  of  the 
L.  P.  cylinder  leaked  badly,  and  the  crank-end  valve  a  consid- 
erable amount;  but  as  near  as  could  be  judged  under  these 
circumstances  the  exhaust  valves  and  piston  were  fairly  tight. 
The  load  was  cotton  machinery.  Three  tests  were  made  with 
different  receiver  pressures,  and  one  test  was  made  with 
steam  shut  off  from  jackets  and  reheater. 

On  test  B  the  water  condensed  in  the  jackets  and  reheater 
tubes  amounted  to  681  Ibs.  per  hour,  or  7.7%  of  the  total. 
This  is  included  in  the  total  quantity  given  in  the  table. 


ENGINE  No.  47.  187 

A  noticeable  feature  of  these  results  is  the  systematic  in- 
crease in  the  steam  consumption  per  H.  P.  per  hour  as  the 
receiver  pressure  was  raised.  This  may  have  been  due  to  the 
increased  leakage  of  the  L.  P.  steam  valves. 

A  comparison  of  the  jacket  tests  reveals  a  gain  due  to  the 
jackets  of  0.24  Ibs.  per  H.  P.  per  hour,  or  about  2%.  Although 
this  is  not  a  marked  difference,  it  is  evident  from  an  analysis 
of  the  diagrams  that  the  jackets  had  a  considerable  effect  upon 
the  distribution  of  the  steam,  especially  in  increasing  the 
power  developed  by  the  L.  P.  cylinder  and  the  quantity  of 
steam  accounted  for  by  the  diagram  for  that  cylinder. 


UNIVERSITY 
"   CALIFO* 


ENGINE  No.  47a 


H.P.  Head  End 


-140 
-120 
-100 
-  80 
-60 
-40 
-20 
I—  0 


H.P.  Crank  End 


-140 
-120 

-100 
80 

-  60 
-40 
-20 

-  0 


L.P.  Head  End 


r  10 

-  5 

-  0 

-  5 
IO 


L.P,  Crank  End 


r  10 

-  5 

-  0 

-  5 

-  10 


ENGINE  No.  47b 


H.P.  Head  End 


-140 
-120 
-100 
-80 
-60 
—40 
-20 
—  0 

r-140 
-120 
-100 
-80 
-60 
-40 
-20 
-  0 


H.P.  Crank  End 


L.P.  Head  End 


L.P.  Crank  End 


ENGINE    No.  48. 

Compound  Condensing  Engine. 


H.  P. 

CYLINDER. 

L.  P. 
CYLINDER. 

Kind  of  engine     
Number  of  cylinders 

Four 
1 
28A 

5 
5 
4 

.185 
1 

Fairlj 

valve 
1 
54 
two  7 
5 
6 

.682 
3.69 

-  tight 

Diameter  of  cylinder                         .          ins. 

Diameter  of  piston  rod       ins. 

Stroke  of  piston  ft. 

Clearance   % 

Horse-power  constant  for  one  Ib.  m.e.p. 
one  revolution  per  minute    .     .     .H.P. 
Ratio  of  areas  of  cylinders     .... 
Condition  of  valves  and  pistons  regard- 
in0"  leakaee   . 

Data  and  Results  of  Feed  -  Water  Tests. 


TEST. 
CONDITIONS  REGARDING  USE  OF  REHEATER. 

A. 
REHEATER 

ON 

B. 
REHEAT'R 

OFF. 

c. 

REHEATER 

ON. 

Character  of  steam  
Duration    hrs. 
Total  weight  of  feed-water  consumed  .     Ibs. 
Total  feed-water  consumed  per  hour        Ibs. 
Feed-water  consumed  per  hour  by  air- 
pump             

Sup'd  12° 
5.0 
101,465. 
20,293. 

2,063. 

Sup'd  13° 
5.0 
97,856. 
19,571.2 

2030. 

Sup'd  20o 
5.0 
105,355. 
21,071. 

1,744. 

Feed-water    consumed    per    hour    by 
engine  alone       Ibs. 
Pressure  in  steam  pipe  above  atmos.     Ibs. 
Pressure  in  receiver  above  atmosphere    Ibs. 
Vacuum  in  condenser  ins. 

18,230. 
125.9 
11.4 

27 

17,541.2 
121.5 
10.1 

27 

19,327. 

100.2 
10.2 

27  4 

Revolutions  per  minute     
Mean  effective  pressure,  H.  P.  cylinder    Ibs. 
Mean  effective  pressure  L.  P.  cylinder    Ibs. 
Indicated  horse-power,  H.  P.  cylinder  H.P. 
Indicated  horse-power,  L.  P.  cylinder    H.P. 
Indicated  horse-power,  whole  engine  .  H.P. 
Total  feed-water  consumed  per  I.H.  P. 
per  hour                   Ibs. 

77. 
46.11 
12.08 
656.51 
634.62 
1,291.13 

*  15.72 

76.69 
46.47 
11.34 
658.90 
593.31 
1,252.21 

15.63 

76.68 
45.29 
12.22 
642.16 
639.57 
1,281.73 

16.44 

Feed-water  per  I.    H.    P.    per   hour, 
engine  alone                                          Ibs 

14  12 

14.01 

15  08 

*  This  refers  to  steam  used  by  the  engine  alone. 


190 


ENGINE  No.   48. 


191 


Measurements  based  on  Sample  Diagrams. 


TEST. 

A. 

B. 

c. 

H.P.CY. 

L.P.Cv. 

H.P.CY. 

L.P.CY. 

H.P.CY. 

L.P.CY. 

Initial  pressure  above 

atmosphere  .     .     .      Ibs. 

119.5 

13.1 

113.3 

11.8 

94.8 

10. 

Corresponding    steam 

pipe     or    receiver 

pressure    ....     Ibs. 

127. 

12.3 

121. 

9.8 

100. 

10.3 

Cut-off  pres.  above  zero    Ibs. 

115.3 

22. 

112  5 

20.7 

93. 

18.8 

Release  pres.  above  zero  Ibs. 

38.2 

8.3 

37.7 

7.7 

39. 

8.5 

Mean  effective  press.  .      Ibs. 

46.62 

12.29 

46.99 

11.5 

45.11 

12.25 

Back  pressure  at  mid 

stroke  above  or  be- 

low atmosphere     .      Ibs. 

+18.5 

—10.7 

+16.5 

—10.7 

+13.7 

-11.3 

Proportion    of    stroke 

*' 

completed  at  cut-off 

.294 

.326 

.31 

?326 

.432 

.416 

Steam    accounted   for 

« 

at  cut-off  ....     Ibs. 

11.18 

10.66 

11.99 

10.33 

12.41 

12.18 

Steam    accounted   for 

at  release      .     .     .      Ibs. 

12.27 

11.55 

12.63 

11. 

13.04 

12.25 

Proportion     of      feed 

water  accounted  for 

at  cut-off      .     .     . 

.792 

.755 

.856 

.737 

.823 

.808 

Proportion     of     feed 

water  accounted  for 

at  release      .     .     . 

.869 

.818 

.901 

.785 

.865 

.812 

Engine  No.  48  is  a  horizontal  cross  compound,  with  un- 
jacketed  cylinders  and  a  reheating  receiver.  The  valves  are 
plain  slides.  The  condenser  is  of  the  jet  type  with  steam- 
driven  air-pump,  the  steam  used  for  which  was  determined 
and  allowed  for.  The  boilers  are  of  the  vertical  fire-tube  type, 
furnishing  slightly  superheated  steam.  The  crank  end  exhaust 
valve  of  the  H.  P  cylinder  leaked  considerably,  but  with  this 
exception  the  valves  and  pistons  were  practically  tight.  The 
load  was  cotton  machinery. 

A  comparison  of  tests  A  and  C  shows  the  effect  of  two 
widely  different  pressures  upon  the  economy,  one  being  125.9 
Ibs.,  and  the  other  100.2  Ibs.  The  reduction  of  pressure  in- 
creased the  consumption  from  14.12  Ibs.  per  I.  H.  P.  per  hour 
to  15.08  Ibs.,  or  nearly  7  %. 

Test  B  as  compared  with  test  A  exhibits  the  effect  of 
shutting  off  the  reheater.  There  is  a  slight  loss  of  economy ; 
but  as  the  difference  is  within  the  limits  of  errors  of  measure- 


192  ENGINE    TESTS. 

ment  and  accidental  difference  of  condition,  the  most  that  can 
be  said  is  that  the  economy  produced  by  the  reheater  was  in 
this  case  inappreciable.  On  test  A  there  was  648  Ibs.  of  steam 
per  hour  condensed  and  drawn  off  from  the  reheater  tubes. 
This  is  4  %  of  the  quantity  used  by  the  engine.  The  effect  of 
the  heat  derived  from  this  source  is  seen  in  the  increased 
power  developed  by  the  L.  P.  cylinder,  and  the  increase  in  the 
amount  of  steam  accounted  for  in  the  L.  P.  cylinder  as  com- 
pared with  that  in  the  H.  P.  cylinder. 

The  comparatively  large  amount  of  steam  used  by  the  air- 
pump  is  noticeable,  being  about  10  %  of  the  entire  quantity 
on  Test  A. 


I2Q— i 

100- 

80- 

60- 

40- 

20- 

0- 


ENGINENo.  48a 


H.P.  Cyl.  Head  End 


H.P.  Crank  End 


-120 
-100 

-  80 

-  GO 

-  40 

-  20 

-  0 


UP.  Head  End 


-    15 

-  10 

5 
0 

-  5 
L    10 


10- 

6- 
0 

5- 
10- 


L.P.  Crank  End 


ENGINE  No.  48b 


120- 
100- 
80- 
60- 
40- 
20- 
0- 


H.P.  Head  End 


H. P.  Crank  End 


-120 
100 
30 
60 
40 

-  20 

-  0 


L.P.  Head  End 


15- 

10 
6- 
0- 
6- 

10- 


L.P.  Crank  End 


ENGINE  No.48c 


100- 
80- 
60- 
40 
20- 
0- 


H.P.  Head  End 


H.P.  Crank  End 


100 
80 
60 
40 
20 
0 


L.P.  Head  End 


5- 
0- 
5- 
10- 


L.P.  Crank  End 


ENGINE   No.  49. 


Compound  Condensing  Engine. 


H.P. 
CYLINDER. 

L.  P. 
CYLINDER. 

Kind  of  engine     .     .     .     ....     .     . 
Number  of  cylinders      

Four  valv 
1 

B  (Corliss) 
1 

Diameter  of  cylinder     .     ,     .     .'     .     .     ins. 
Diameter  of  piston  rod      .....     ins. 
Stroke  of  piston  ........       ft. 
Clearance                                                        % 

24 
6A 

5 
3 

44 
51 
5 
4i 

H.  P.  constant  for  1  Ib.  m.  e.  p.  one 
revolution  per  minute    ....  H.P. 
Ratio  of  areas  of  cylinders     .... 
Condition  of  valves  and  pistons  regard- 
ing leakage   

.1337 

1 
Some 
leakage 

.457 
3.43 
Fairly 
tight 

Data  and  Results  of  Feed  -  Water  Test. 


Character  of  steam    .     .     .     .     .     .     .     ." 

Duration .     .     . 

Weight  of  feed-water  consumed  .     .     .     . 

Feed-water  consumed  per  hour    .... 

Pressure  in  steam  pipe  above  atmosphere  . 
Pressure  in  receiver  above  atmosphere . 
Vacuum  in  condenser    .     .?   .     ....     . 

Revolutions  per  minute       ...... 

Mean  effective  pressure,  H.  P.  cylinder  . 
Mean  effective  pressure,  L.  P.  cylinder 
Indicated  horse-power,  H.  P.  cylinder 
Indicated  horse-power,  L.  P.  cylinder  . 
Indicated  horse-power,  whole  engine  . 
Feed-water  consumed  per  I.  H.  P.  per  hour 


Ordinary 


4.75 

hie. 

58.832 

Ibs. 

12,385.6 

Ibs. 

115.4 

Ibs. 

6.8 

Ibs. 

28.4 

ins. 

71.3 

rev. 

47.93 

Ibs. 

12.71 

Ibs. 

457.9 

H.P. 

415 

H.P. 

872.9 

H.P. 

14.18 

Ibs. 

Measurements  based  on  Sample  Diagrams. 


H.P. 

CYLINDER. 

L.  P. 
CYLINDER. 

Initial  pressure  above  atmosphere   .     ." 
Corresponding  steam-pipe  and  receiver 
pressure     . 
Cut-off  pressure  above  zero    .     .     .   '  . 
Release  pressure  above  zero  .... 
Mean  effective  pressure      
Back  pressure  at  mid  stroke  above  or 
below  atmosphere                  .     . 

Ibs. 

Ibs. 
Ibs. 
Ibs. 
Ibs. 

Ibs. 

100.9 

114 
104.4 
36.3 
49.03 

+12  7 

9.3 

10.6 
19. 
8.6 
12.71 

—11.8 

Proportion  of  stroke  completed  at  cut- 
off    

.33 

.404 

Steam  accounted  for  at  cut-off    .     .     . 
Steam  accounted  for  at  release    . 
Proportion  of  feed-water  accounted  for 
at  cut-off            

Ibs. 
Ibs. 

12.28 
12.95 

.866 

10.82 
11.78 

.763 

Proportion  of  feed-water  accounted  for 
at  release       .     .     .....     .     . 

.913 

.831 

196 


ENGINE  No.  49.  197 

Engine  No.  49  is  a  cross  compound  horizontal  engine  with 
jacketed  cylinders,  and  a  jet  condenser  operated  by  a  direct  con- 
nected air-pump.  The  jacket  spaces  are  of  the  kind  which  allow 
the  steam  to  pass  through  them  before  entering  the  steam  chest 
of  either  cylinder,  and  the  water  of  condensation  drains  to  waste. 
Steam  is  supplied  from  water-tube  boilers  through  a  pipe  about 
100  feet  in  length,  which  is  trapped  near  the  throttle  valve. 
Steam  lost  by  condensation  in  this  pipe,  and  that  used  for  cer- 
tain heating  purposes,  was  determined  independently,  and 
allowed  for.  The  front-end  steam  valve  of  the  high-pressure 
cylinder  leaked  badly.  With  this  exception,  the  valves  and 
pistons  throughout  were  in  fairly  good  condition.  The  load 
was  cotton  machinery. 

Considering  the  proportion  which  is  borne  by  the  stearn 
accounted  for  to  the  feed-water  consumption  in  the  high-pres- 
sure cylinder,  the  result  of  this  test,  14.18  Ibs.  per.  I.  H.  P. 
per  hour,  must  be  considered  as  an  exceptionally  good  per- 
formance. 


ENGINE  No.49 


100- 
80- 

60- 
40- 
20- 


H.P.  Head  End 


H. P.  Crank  End 


-100 

-  80 

-  60 

-  40 

-  20 
—     0 


L.P.  Head  End 


-  10 

-  5 
0 

-  5 

-  10 


L.P.  Crank  End 


-  10 

-  5 
-  0 

-  5 

-  10 


ENGINE    No.  50. 

Compound  Condensing  Engine. 


H.  P. 

CYLINDER. 

L.  P. 
CYLINDER 

Kind  of  engine       .     .     .     .     .     .     .     .     . 

Four  valv 
1 

61 
2.5 

.1631 
1 

Some 
leakage 

e  (Corliss) 
1 
431 
5H 
6 
4 

.5577 
3.42 
Fairly 

tight 

Number  of  cylinders  \ 
Diameter  of  cylinders     ins. 
Diameter  of  piston  rod   ins. 
Stroke  of  piston     ft. 
Clearance                                         ....         x. 

H.  P.  constant  for  1  Ib.  m.  e.  p.  one  rev- 
olution per  inin  H.P. 
Ratio  of  areas  of  cylinders       

Condition  of  valves  and  pistons  regarding 
leakage  

Data  and  Results  of  Feed  -Water  Test. 


Character  of  steam      '..     . 
Duration                                                        . 

.     .    Superheati 
5 

3d  30° 
hrs. 
Ibs. 
Ibs. 
Ibs. 
Ibs. 
ins. 

Ibs. 
Ibs. 
H.P. 
H.P. 
H.P. 
Ibs. 

Weight  of  feed-water  consumed     
Feed-water  consumed  per  hour      .     .     .     .     .     .     ... 
Pressure  in  steam  pipe  above  atmosphere    .     .     .     .     . 
Pressure  in  receiver  above  atmosphere    .... 

.     .  53,003 
.     .  10,600.7 
.     .        108.1 
'.     .          13  4 

Vacuum  in  condenser                                   '  .     .     .   • 

27  2 

Revolutions  per  minute    

Mean  effective  pressure    H   P   cylinder 

.     .          61.4 

35  77 

Mean  effective  pressure,  L.  P.  cylinder  
Indicated  horse-power   H   P   cylinder 

.     .          12.86 

358  2 

Indicated  horse  power  Ij   P   cylinder 

440  2 

Indicated  horse-power,  whole  engine       
Feed-water  consumed  Der  I.  H.  P.  per  hour 

.     .        798.4 
13.28 

Measurements  based  on  Sample  Diagrams. 


H.P. 
CYLINDER. 

L.  P. 
CYLINDER. 

Initial  pressure  above  atmosphere  . 
Corresponding  steam-pipe  and  receiver 
pressure 

Ibs. 
Ibs 

94.9 

108 

12.8 
13  4 

Cut-off  pressure  above  zero    .... 
Release  pressure  above  zero  .... 
Mean  effective  pressure 

Ibs. 
Ibs. 
Ibs 

102:6 
28.1 
35  78 

22.4 
6.9 

12  72 

Back  pressure  at  mid  stroke,  above  or 
below  atmosphere  

Ibs 

+  16  3 

—  12  4 

Proportion  of  stroke  completed  at  cut-off 
Steam  accounted  for  at  cut-off    .     .     . 
Steam  accounted  for  at  release    .     .     . 
Proportion  of  feed-water  accounted  for 
at  cut-off  
Proportion  of  feed-water  accounted  for 
at  release       

Ibs. 
Ibs. 

.274 
11.81 
11.97 

.889 
.901 

.27 
10.23 
10.87 

.77 
.819 

199 


200  ENGINE    TESTS. 

Engine  No.  50  is  a  cross  compound  engine  with  horizontal 
steam  jacketed  cylinders  and  a  jet  condenser  operated  by  a 
direct  connected  air-pump.  The  jacket  of  the  L.  P.  cylinder 
forms  a  thoroughfare  through  which  the  steam  is  supplied  to 
the  steam  chest,  the  steam  being  admitted  through  the  bottom. 
The  jacket  of  the  H.  P.  cylinder  drains  into  the  receiver.  The 
drip  of  the  receiver  and  of  the  low-pressure  jacket  passes  to  a 
pump  operated  by  the  engine,  and  thence  to  flue  heaters,  or 
"  regenerators  "  as  they  are  called,  which  are  located  in  the  flue 
of  the  boilers.  The  steam  generated  in  these  heaters  returns 
to  the  receiver.  By  this  means  the  low-pressure  cylinder 
receives  benefit  from  some  of  the  heat  which  would  otherwise 
escape  from  the  boilers  to  the  chimney.  Steam  is  supplied 
from  vertical  boilers,  which  superheat.  The  exact  amount  of 
superheating  was  not  determined ;  but  from  the  operation  of 
boilers  of  similar  type,  the  temperature  was  probably  30°  above 
the  normal.  The  piston  of  the  high-pressure  cylinder  leaked 
considerable,  but  the  piston  of  the  low-pressure  cylinder  and 
the  valves  of  both  were  in  good  condition.  The  load  was  that 
of  a  cotton  mill. 

The  results  of  this  test  are  interesting  on  account  of  the 
means  provided  for  reheating  the  steam  and  re-evaporating  the 
jacket  water  for  the  use  of  the  low-pressure  cylinder,  employ- 
ing for  this  purpose  the  heat  of  the  waste  gases  of  the  boilers. 
Comparing  this  test  with  that  made  on  Engine  No.  49,  where 
no  such  provision  was  made,  the  difference  is  quite  marked, 
being  .9  of  a  pound  per  I.  H.  P.  per  hour,  or  nearly  7%.  It  is 
difficult  to  determine  by  this  comparison  how  much,  if  any, 
effect  was  produced  by  the  reheating  process,  because  of  the 
difference  in  the  condition  of  the  steam;  and,  furthermore, 
because  there  was  quite  a  difference  in  the  degree  of  expansion, 
the  cut-off  in  the  high-pressure  cylinder  of  one  engine  being 
.33,  and  in  the  other  .27.  The  effect  of  the  reheating  is  not 
sufficiently  marked  to  show  in  the  analysis  of  the  diagrams. 
It  appears  that  there  was  no  more  steam  accounted  for  in  the 
low-pressure  cylinder  in  one  case  than  in  the  other.  A  greater 
quantity  might  be  expected  if  there  was  a  marked  effect  pro- 
duced by  the  reheating. 


ENGINE  No.  50 


100- 
80- 
60- 
40- 
20- 
0— 


H.P.  Head  End 


H.P.  Crank  End 


100 
-80 
-60 
—  40 
-20 
-  0 


L.P.  Head  End 


L.P,  Crank  End 


ENGINE    No.  51. 


Compound  Condensing  Engine. 


H.  P. 
CYLINDER. 

L.  P. 
CYLINDER. 

Kind  of  engine     .     ,     .           .... 
Number  of  cylinders     ...... 
Diameter  of  cylinder                                   ins 

Four 

1 
18 

valve 
1 

48i 

Diameter  of  piston  rod       ....          ins. 
Stroke  of  piston  .     .                                      ft 

31 
4 

41 
4 

Clearance    ....                                  % 

2 

it 

H.  P.  constant  for  one  Ib.  m.  e.  p.  one 
revolution  per  minute     .     .     .     .  H.P. 
Ratio  of  areas  of  cylinders     .... 
Condition  of  valves  and  pistons  regard- 
ins:  leakage    . 

.0604 
1 

Some 
leakaa-e 

.4412 
7.3 

Some 
leakage 

Data  and  Results  of  Feed -Water  Tests. 


TEST. 

A. 

B. 

C. 

Character  of  steam,  degs.  superh'g 

15.7 

16.4 

12.2 

Duration                                                         hrs 

5 

5 

5 

Weight  of  feed-water  consumed      .     .     Ibs. 

41,210 

39,583 

39,174 

Feed-water  consumed  per  hour  .     .     . 

8,242 

7,916.6 

7,834.8 

Pressure  in  steam  pipe  above  atmos. 

149.7 

150.4 

150.2 

Pressure  in  receiver      Ibs. 

5.4 

9.1 

12.9 

Vacuum  in  condenser  ins. 

26.9 

26.4 

26.6 

Revolutions  per  minute     rev. 

80.04 

80.14 

80 

Mean  effective  pressure,  H.  P.  cylinder    Ibs. 

72.44 

65.89 

61.9 

Mean  effective  pressure,  L.  P.  cylinder    Ibs. 

9.03 

9.59 

10.2 

Indicated  horse-power,  H.P.  cylinder.  H.P. 

350.9 

318.9 

299.3 

Indicated  horse-power,  L.  P.  cylinder  .  H.P. 

390.6 

339.2 

359.8 

Indicated  horse-power,  whole  engine  .  H.P. 

670.5 

658.1 

659.1 

Feed-water  cons,  per  I.  H.  P.  per  hour   Ibs. 

12.29 

12.03 

11.89 

Measurements  Based  on  Sample  Diagrams. 


TEST. 

i 

L. 

( 

H.P. 

L.P. 

H.P. 

L.P. 

Initial  pressure  above  atmosphere   .     .     Ibs. 

143.9 

5.2 

143. 

14.5 

Corresp.  steam-pipe  and  receiver  pres.     Ibs. 

151 

*5.5 

150.5 

*12.8 

Cut-off  pressure  above  zero    ....     Ibs. 

149 

15.4 

145.9 

24.7 

Release  pressure  above  zero  ....     Ibs. 

42.5 

5.2 

43. 

5.2 

Mean  effective  pressure     Ibs. 

72.7 

9.08 

62.27 

10.23 

Back  pressure  at  mid  stroke  above  or 

below  atmosphere       Ibs. 

+  6 

-13.1 

+  16.5 

-13 

Proportion  of  stroke  completed  at  cut-off 

.285 

.323 

.285 

.176 

Steam  accounted  for  at  cut-off    .     .     .     Ibs. 

9.54 

9.07 

9.21 

7.96 

Steam  accounted  for  at  release   .     .     .     Ibs. 

9.62 

8.88 

9.58 

8.43 

Proportion  of  feed-water  accounted  for 

at  cut-off                            .... 

.77 

.732 

.769 

.654 

Proportion  of  feed-  water  accounted  for 

at  release    

.776 

.716 

.8 

.704 

*  Not  corrected. 

NOTE.  — The  weight  of  steam  condensed  in  all  the  jackets  averaged,  for  the 
three  trials,  9.5  %  of  the  total  steam  consumed  ;  and  this  is  included  in  the 
quantities  given. 

202 


ENGINE  No.    51.  203 

Engine  No.  51  is  a  horizontal  cross  compound,  with  jacketed 
cylinders  and  a  reheater.  The  condenser  is  of  the  siphon  type, 
and  water  is  supplied  by  gravity.  Both  the  barrel  and  the 
heads  of  the  high-pressure  cylinder  are  jacketed,  but  only  the 
barrel  of  the  L.  P.  cylinder.  The  reheater  has  sufficient  sur- 
face to  superheat  the  steam,  although  not  sufficient  to  prevent 
some  water  condensing  in  the  bottom  of  the  shell,  from  which 
it  is  drawn  away  by  a  trap.  The  jackets  are  drained  by  traps 
which  discharge  to  waste.  The  valves  are  all  of  the  gridiron 
type.  Steam  is  supplied  from  vertical  boilers  which  super- 
heat. The  piston  of  the  H.  P.  cylinder  was  found  to  show 
some  leakage.  The  low-pressure  exhaust  valve  at  the  crank 
end  leaked  quite  badly.  The  piston  of  the  L.  P.  cylinder  and 
the  remaining  valves  were  in  good  condition.  Three  tests 
were  made,  using  three  different  receiver  pressures. 

These  tests  are  of  interest  on  account  of  the  unusual  ratio 
of  volumes  of  the  cylinders.  This  ratio  is  about  the  same  as 
that  which  is  common  practice  between  the  low-pressure  and 
high-pressure  cylinder  of  a  triple  expansion  engine.  This 
large  ratio  taken  in  conjunction  with  the  high  initial  pressure, 
and  the  fact  that  the  steam  was  slightly  superheated,  furnishes 
an  explanation  for  the  economical  results  obtained,  which  are 
unusual. 

Comparing  the  three  tests  together,  it  appears  that  there  was 
a  gradual  improvement  produced  by  increasing  the  receiver 
pressure,  the  best  result  being  obtained  when  that  pressure  was 
the  highest. 

In  this  connection,  it  is  noticeable  that  as  the  receiver  pres- 
sure increased,  and  the  cut-off  in  the  low-pressure  cylinder 
became  less,  the  steam  accounted  for  by  the  low-pressure 
cylinder  became  less. 


ENGINE  No.SIa 


140- 
120- 
100- 
80- 
60- 
40- 
20- 
0- 


H.P.  Head  End 


H.P.  Crank  End 


-140 
120 
100 
•80 
GO 
•40 
-20 
-  0 


L.P.  Head  End 


L.P.  Crank  End 


140- 

120- 

100- 

80- 

60- 

40- 

20- 

0- 


ENGINENo.SIc 


H. P.  Head  End 


H.P.  Crank  End 


-140 
-120 
-100 

-  80 
-60 
-40 
-20 

-  0 


L.P.  Head  End 


L.P.  Crank  End 


ENGINE  No.  52. 


Compound  Condensing  Engine. 


H.P. 
CYLINDER. 

L.  P. 

CYLINDER. 

Kind  of  engine     

Four 

^alve 

Number  of  cylinders     
Diameter  of  cylinder     .   ins. 

Diameter  of  piston  rod       ins. 
Stroke  of  piston  ....                           ft 

2 
14TV 
34 
4 

2 
36* 

one  3k 
one  4^ 
4 

Clearance   % 

2 

2£ 

H.  P.  Constant  for  one  Ib.  m.e.p.,  one 
rev.  per  minute      H.P. 
Ratio  of  areas  of  cylinders     .... 
Condition  of  valves  and  pistons  regard- 
ins:  leakage   . 

.0367  each 
1 

Some  leakage 

.2456  each 
6.69  both 

Some  leakage 

Data  and  Results  of  Feed -Water  Tests. 


TEST. 
JACKETS  ON  OR  OFF. 

A. 
ON. 

B. 
ON. 

C. 
ON. 

D. 
OFF. 

Character  of  steam       .... 

Ordinary 

Ordinary 

Ordinary 

Ordinary 

Duration  hrs. 

5.0 

5.06 

5.03 

4.5 

Weight  of  feed-water  consumed     Ibs. 

47,045.0 

49,720.0 

48,389.0 

43,321.0 

Feed-water  consumed  per  hour      Ibs. 

9,409.0 

9,812.5 

9,614.4 

9,626.9 

Pres.  in  steam  pipe  above  atmos.     Ibs. 

144.2 

144.1 

143.8 

144.1 

Pres.  in  receiver  above  atmos.        Ibs. 

4.9 

8.6 

12.2 

12.3 

Vacuum  in  condenser  ....     ins. 

25.3 

25.2 

25.0 

24.9 

Revolutions  per  minute    .     .     .    rev. 

77.45 

76.65 

76.86 

78.89 

Mean  effective  pressure,  H.P.  cyl.  Ibs. 

61.12 

60.82 

57.29 

60.53 

Mean  effective  pressure,  L.P.  cyl.  Ibs. 

9.76 

10.6 

11.0 

9.66 

Indicated  horse-power,  H.P.  cyl.  H.P. 

347.63 

342.48 

323.48 

350.79 

Indicated  horse-power,  L.P.  cyl.  H.P. 

371.22 

398.84 

415.29 

374.41 

Indicated  H.  P.  whole  engine     .  H.P. 

718.85 

741.32 

738.77 

725.2 

Feed-water  consumed  per  I.  H.P. 

per  hour       Ibs. 

13.09 

13.23 

13.01 

13.27 

Measurements  based  on  Sample  Diagrams. 


TEST. 

< 

r 

>. 

JACKETS  ON  OR  OFF. 

ON. 

ON. 

OFF. 

OFF. 

Initial  pressure  above  atmosphere  .     .     Ibs. 
Corresponding  steam-pipe  and  receiver 
pressure  above  atmosphere       .     .     Ibs. 
Cut-off  pressure  above  zero    ....      Ibs. 
Release  pressure  above  zero  ....     Ibs. 
Mean  effective  pressure                               Ibs 

H.P. 
139.7 

145.0 
140.0 
41.3 

57  64 

L.P. 

13.0 

12.3 
22.4 
5.6 

11  07 

H.  P. 
139.9 

144.5 

140.0 
44.0 
60  3 

L.  P. 
11.7 

12.8 
21.4 
5.2 

9  58 

Back  pressure  at  mid  stroke  above  or 
below  atmosphere  Ibs. 

+13.8 

-12.2 

+14.1 

—12.2 

Proportion  of  stroke  completed  at  cut-off 
Steam  accounted  for  at  cut-off   .     .     .     Ibs. 
Steam  accounted  for  at  release  .     .     .     Ibs. 
Proportion  of  feed-water  ace.  for  at  cut-off 
Proportion  of  feed-water  accounted  for 
at  release      

.268 
8.48 
9.26 
.651 

.712 

.236 
10.23 
10.62 
.786 

.816 

.293 
9.75 
10.27 
.734 

.774 

.213 
8.71 
9.79 
.655 

.73 

206 


ENGINE   No.   52.  207 

Engine  No.  52  is  a  pair  of  horizontal  tandem  compounds, 
having  jacketed  cylinders  and  reheating  receivers,  the  con- 
densers being  of  the  siphon  type,  to  which  water  is  supplied 
by  gravity.  The  H.  P.  cylinders  are  jacketed  all  over,  but  the 
L.  P.  cylinders  have  only  the  barrels  jacketed.  As  in  the  case 
of  Engine  No.  51,  the  reheaters  are  provided  with  sufficient 
surface  to  superheat  the  steam  passing  to  the  low-pressure 
cylinders,  the  water  which  remains  being  trapped.  The  valves 
are  all  of  the  gridiron  type.  Steam  is  supplied  by  horizontal 
return  tubular  boilers,  and  at  the  throttle  valves  it  contained 
.1  of  1  %  of  moisture.  The  H.  P.  pistons  leaked  to  some  ex- 
tent, and  the  head-end  exhaust  valve  of  the  left-hand  low- 
pressure  cylinder  leaked  a  considerable  amount.  The  pistons 
of  the  H.  P.  cylinder  and  the  remaining  valves  were  fairly 
tight.  The  load  was  cotton  machinery. 

Three  trials  were  made  with  three  different  receiver  pres- 
sures, and  a  fourth  trial  with  steam  shut  off  from  the  jackets 
and  the  reheating  tubes. 

Comparing  the  results  of  these  tests  with  those  made  on 
Engine  No.  51,  which  is  of  the  same  general  type  and  of 
about  the  same  power,  but  having  only  half  the  number  of 
cylinders,  there  is  a  striking  difference.  This  engine  did  not 
have  the  benefit  of  superheated  steam  as  did  Engine  No.  51, 
and  this  difference  in  the  conditions  must  be  taken  into  account ; 
but  it  is  hardly  possible  that  the  whole  of  the  difference,  which 
is  about  9  %,  could  be  produced  in  this  way.  There  may  be 
some  difference,  also,  in  the  amount  of  leakage  of  the  two  en- 
gines. Engine  No.  51  had  the  benefit  of  the  best  vacuum. 
Making  all  allowances  for  these  differences,  it  is  quite  certain 
that  the  size  of  the  cylinders  had  some  effect  upon  the  results. 
The  action  of  the  steam  in  the  cylinders  is  quite  different  in 
No.  52  from  what  it  is  in  No.  51  ;  but  it  will  be  noticed  that 
steam  accounted  for  in  the  low-pressure  cylinders  is  greater  than 
that  shown  in  the  high  pressure  cylinders,  whereas  in  Engine 
No.  51  the  contrary  is  true. 

Comparing  Test  "  C  "  with  jackets  on,  and  Test  "  D  "  with 
jackets  off,  the  difference  in  the  economy  shown  is  only  .26  of 


208  ENGINE    TESTS. 

a  pound,  or  about  2  %.  The  nature  of  the  action  which  the 
jackets  produced  is  shown  in  the  analysis  of  the  diagrams. 
With  the  jackets  on,  the  steam  accounted  for  in  the  low-pres- 
sure cylinder  is  the  greatest ;  whereas,  with  the  jackets  off,  the 
steam  accounted  for  in  that  cylinder  is  the  least. 

Another  noticeable  thing  in  the  action  of  the  jackets  is  in 
the  distribution  of  the  power  between  the  cylinders.  With 
jackets  on,  the  low-pressure  cylinders  developed  92  horse- 
power more  than  the  high-pressure  cylinders,  or  about  30  °/0  ; 
whereas,  with  jackets  off,  the  increase  was  only  24  horse-power, 
or  about  7  %. 

NOTE.  —  The  quantity  of  steam  condensed  in  the  jackets  on  the  first  three 
trials  was  respectively,  11.4  %,  10.8  %,  and  10.8  %  of  the  total  quantity  con- 
sumed ;  and  these  are  included  in  the  figures  given  in  the  tables. 


ENGINE  No.  52c 


140- 
120- 
100- 
80- 
60- 
40- 
20- 
0- 


R.H.H.P.  Head  End 


R.H.H.P.  Crank  End 


-140 

120 

100 

-  80 

60 

40 

20 

0 


10- 

5  — 
0- 
5- 
10 


R.H.L.P.  Head  End 


R.H.L.P.  Crank  End 


ENGINE  No.  52c 


I40-, 

120- 

100- 

80- 

60- 

40- 

20- 

0- 


L.H.H.P.  Head  End 


L.H.H.P.  Crank  End 


140 
120 
100 
80 
60 
40 
20 
-  0 


L.H.L.P.  Head  End 


15- 
10- 
5- 

o- 

5- 

10- 


L.H.L.P.  Crank  End 


ENGINE  No.  52d 


140— 

120- 

100- 

80- 

60- 

40- 

20- 

0- 


R.H.H.P.  Head  End 


R.H.H.P.  Crank  End 


-140 
—120 
-100 

-  80 

—  60 

-  40 

—  20 

—  O 


15- 
10- 
5— 
0— 
5- 
10- 


R.H.L.P.  Head  End 


R.H.L.P.  Crank  End 


-  15 

—  10 

-  5 

—  0 

—  5 

-  10 


ENGINE  No.  52d 


140— 

ISO— 

100- 

80- 

60- 

40- 

20- 

0- 


L.H.H.P.  Head  End 


L.H.H.P.  Crank  End 


-140 
120 
100 
80 
-60 
-40 

-  20 

-  0 


L.H.L.P.  Head  End 


15 
10 
5 
0 
5 
10 


15— 
10- 

5- 

O- 

5 

10- 


L.H.L.P.  Crank  End 


ENGINE    No.  53. 

Compound  Condensing  Engine. 


H.P.  CYLINDER. 

L.P.  CYLINDER. 

Kind  of  engine                   

Four  vah 

1 
18 

31 

4 
3 

.0608 
1 

Fairly  tight 

re  (Corliss) 
30 

4* 
3 

.1685 

2.77 

Fairly  tight 

Number  of  cylinders      
Diameter  of  cylinder                                   ins 

Diameter  of  piston  rod                                ins 

Stroke  of  piston  ft. 
Clearance   % 
H.  P.  constant  for  one  Ib.  m.  e.  p.,  one 
rev.  per  min  H.P. 
Ratio  of  areas  of  cylinders     .... 
Condition  of  valves  and  pistons  regard- 
in0"  leakage 

Data  and  Results  of  Feed -Water  Tests. 

Character  of  steam 

Duration 

Weight  of  feed- water  consumed 

Feed-water  consumed  per  hour 

Pressure  in  steam  pipe  above  atmosphere 

Pressure  in  receiver  above  atmosphere 

Vacuum  in  condenser 

Revolutions  per  minute 

Mean  effective  pressure,  H.  P.  cylinder 

Mean  effective  pressure,  L.  P.  cylinder 

Indicated  horse-power,  H.  P.  cylinder 

Indicated  horse-power,  L.  P.  cylinder 

Indicated  horse-power,  whole  engine 

Feed-water  consumed  per  I.  H.  P.  per  hour 


Ordinary 


3.0 

hrs. 

14,195.0 

Ibs. 

4,731.7 

Ibs. 

114.9 

Ibs. 

15.4 

Ibs. 

25.6 

ins. 

65.5 

rev. 

35.07 

Ibs. 

14.27 

Ibs. 

142.1 

H.P. 

157.6 

H.P. 

299.7 

H.P. 

15.78 

Ibs. 

Measurements  based  on  Sample  Diagrams. 


H.  P. 

CYLINDER. 

L.P. 
CYLINDER. 

Initial  pressure  above  zero       
Cut-off  pressure  above  zero      
Release  pressure  above  zero     
Mean  effective  pressure 

Ibs. 
Ibs. 
Ibs. 
Ibs 

111.9 
111.7 
30.8 
36  65 

14.6 
33.2 

8.7 
14  52 

Back  pressure  at  mid  stroke,  above  or  be- 
low atmosphere  
Proportion  of  stroke  completed  at  cut-off  . 
Steam  accounted  for  at  cut-off      .... 
Steam  accounted  for  at  release     .... 
Proportion  of  feed-water  accounted  for  at 
cut-off 

Ibs. 

Ibs. 
Ibs. 

+  16.7 
.238 
11.31 
9.47 

717 

-  11.8 

13.01 
10.76 

60 

Proportion  of  feed-water  accounted  for  at 
release        .                          ... 

825 

682 

213 


214  ENGINE    TESTS. 

Engine  No.  53  is  a  horizontal  tandem  compound,  with  un- 
jacketed  cylinders  and  jet  condenser  operated  by  an  indepen- 
dent air-pump.  The  steam  from  the  air-pump  was  taken  from 
an  auxiliary  boiler.  The  boilers  are  of  the  water-tube  vertical 
type,  furnishing  steam  slightly  superheated.  The  steam  passes 
through  a  reservoir  at  the  engine,  which  is  drained  by  a  trap 
discharging  to  waste.  The  valves  and  pistons  of  both  cylin- 
ders were  found  to  be  in  fairly  good  condition  throughout. 
The  load  on  the  engine  was  rubber-grinding  machinery  and 
somewhat  variable  in  its  character. 

The  economy  shown  by  this  test,  15.78  Ibs.  per  I.  H.  P.  per 
hour,  is  rather  low  compared  with  other  compound  engines  of 
this  type.  The  explanation  of  this  result  is  found  in  part,  at 
least,  in  the  small  ratios  of  volumes  of  the  two  cylinders.  The 
diagrams  show  the  variable  character  of  the  load. 


ENGINE  No.  53 


H.P.  Head  End 


100 
80 
60 
40 
20 
0 


100  -| 
80- 
60- 
40- 
20- 
0- 


H.P.  Crank  End 


10- 
5- 
0- 
5- 
10- 


L.P.  Head  End 


L.P.  Crank  End 


r-15 
10 

h-  5 
0 
5 
10 


ENGINE    No.  54. 
Compound  Non-Condensing  Engine. 


H.  P.  CYLINDER. 

L.  P.  CYLINDER. 

Kind  of  engine     •' 
Number  of  cylinders     
Diameter  of  cylinder     .     .     ...     .     ins. 
Diameter  of  piston  rod       .     .     .     ...  ins. 
Stroke  of  piston  .     .     .     .     .     .     ."    .     ins. 
Clearance   .               .                                       % 

Single 
1 
12 
2i 
13 
11 

.0073 
1 

Some  1 

valve 

1 
20 
2* 
13 
8 

.0205 
2.81 

eakage 

H.P.  constant  for  one  Ib.  m.e.p.,  one 
revolution  per  minute      .     .     .     .H.P. 
Ratio  of  areas  of  cylinders     .... 
Condition  of  valves  and  pistons  regard- 
ing leakage    

Data  and  Results  of  Feed -Water  Tests. 


TEST. 

A. 

B. 

c. 

Character  of  steam 

Ordinary 

Ordinary 

Ordinary 

Duration     hrs. 
Weight  of  feed-water  consumed      .     .     Ibs. 
Feed-water  consumed  per  hour  .     .     .     Ibs. 
Pressure  in  steam  pipe  above  atmos.    .     Ibs. 
Pressure  in  receiver  above  atmosphere     Ibs. 
Revolutions  per  minute                              rev 

5.0 
17,918.0 
3,583.6 
166.9 
28.2 
275  7 

5.0 
19,815.0 
3,963.0 
166.8 
46.3 
271  2 

5.0 
25,730.0 
5,146.0 
164.6 
60.6 
273  4 

Mean  effective  pressure,  H.  P.  cylinder     Ibs. 
Mean  effective  pressure,  L.  P.  cylinder     Ibs. 
Indicated  horse-power,  H.  P.  cylinder  H.P. 
Indicated  horse-power,  L.  P.  cylinder    H.P. 
Indicated  horse-power,  whole  engine  .  H.P. 
Feed-water  consumed  per  I.  H.  P.  per 
hour     Ibs. 

29.06 
7.94 
58.5 
44.88 
103.37 

24.99 

48.37 
16.5 
95.77 
91.74 
187.51 

21.14 

52.31 

24.58 
104.41 
137.77 

242.18 

21.25 

Measurements  based  on  Sample  Diagrams,  Test  B. 


H.P. 
CYLINDER. 

L.  P. 
CYLINDER. 

Initial  pressure  above  atmosphere    .     . 
Corresponding  steam-pipe  and  receiver 
pressure     '. 
Cut-off  pressure  above  zer  >    . 
Release  pressure  above  zero  .     .     .  '  . 
Mean  effective  pressure      .     .     .     ... 
Back  pressure  at  mid  stroke   above 
atmosphere        » 
Proportion  of  stroke  completed  at  cut- 
off     

Ibs. 

Ibs. 
Ibs. 
Ibs. 
Ibs. 

Ibs. 

157.3 

168.5 
147.5 

77.4 
47.98 

41.6 
.479 

43.0 

46.0 
39.9 
23.9 
16.36 

2.00 
.499 

Steam  accounted  for  at  cut-off    .     .     . 
Steam  accounted  for  at  release    .     .     . 
Proportion  of  feed-water  accounted  for 
at  cut-off 

Ibs. 
Ibs. 

15.73 
15.41 

.744 

14.71 
14.51 

.696 

Proportion  of  feed-  water  accounted  for 
at  release       

.728 

.686 

216 


ENGINE  No.   54.  217 

Engine  No.  54  is  a  vertical  cross  compound  with  unjacketed 
cylinders.  Each  cylinder  has  a  single  balanced  slide  valve, 
and  the  speed  is  controlled  by  a  shaft  governor  operating  on 
the  H.  P.  valve.  The  steam  is  drawn  from  water-tube  boilers 
through  a  considerable  length  of  pipe,  having  headers  and 
separators  which  were  thoroughly  drained,  and  a  calorimeter 
attached  near  the  engine  showed  that  it  was  practically  dry. 
Steam  condensed  from  the  pipes  was  trapped  and  properly 
allowed  for.  The  load  consisted  of  two  dynamos  located  on 
the  engine  shaft.  The  valves  of  both  cylinders  leaked  a  small 
amount,  and  the  piston  of  the  H.  P.  cylinder  leaked  consider- 
ably at  full  pressure.  The  low-pressure  piston  was  tight. 
Three  tests  were  made  with  three  different  loads. 

In  these  tests  there  is  substantial  agreement  between  the 
results  of  tests  "  B  "  and  "  C  "  ;  the  former  being  made  under 
conditions  of  a  medium  load,  and  the  latter  under  what  would 
be  considered  an  overload.  This  reveals  the  advantage  of  com- 
pounding in  engines  of  this  class,  where  by  this  means  the 
benefits  of  expansion  in  the  engine  as  a  whole  are  realized  with- 
out suffering  the  losses  produced  in  either  cylinder  due  to 
early  cut-offs. 


ENGINE  No.  54a 


160- 

120- 

80- 

40- 

0- 


H.P.Top 


-120 

-80 

40 

—    0 


H.P.  Bottom 


30- 

20- 

10- 

0- 


L.P.  Top 


30- 

20- 

10- 

0- 


L.P.  Bottom 


ENGINE  No.  54b 


H.P.  Top 


160- 
120- 

80- 

40- 

0— 


-  160 
-120 
-80 
-40 
—  0 


H.P.  Bottom 


60- 
40- 
30- 
20- 
10- 
0- 


UP.  Top 


50- 

40- 

30- 

20- 

10- 

0- 


L.P.  Bottom 


ENGINE  No.  54c 


H.P.Top 


-160 

-120 
-80 

-40 

L-   0 


160-^ 
120- 
80- 
4O- 
0- 


H.P.  Bottom 


60n 

50- 
40- 
30- 
20- 
10- 
0- 

60^ 
60- 
40- 
30- 
20- 
10- 
0- 


L.P.  Top 


.  Bottom 


ENGINE    No.  55. 

Compound  Condensing  Engine. 


H.P. 
CYLINDER. 

L.  P. 
CYLINDER. 

Kind  of  engine 

Four  valv^  I'flnrlissl 

Number  of  cylinders  

1 

1 

Diameter  of  cylinder  ins. 

28 

56 

Diameter  of  piston  rod    ....     ins. 

51 

6* 

Stroke  of  piston     ft. 

5 

5 

Clearance      % 

3.1 

4.3 

H.P.  Constant  for  one  Ib.  m.  e.  p., 

one  rev.  per  min  H.P. 

.1827 

.7413 

Ratio  of  areas  of  cylinders  . 

1 

4.06 

Condition  of   valves  and    pistons 

regarding  leakage     ,     .     .     . 

Practically  tight 

Data  and  Results  of  Feed -Water  Test. 


Character  of  steam     '    

Or 

dinary 
hrs. 
Ibs. 
Ibs. 
Ibs. 
Ibs. 
ins. 
rev. 
Ibs. 
Ibs. 
H.P. 
H.P. 
H.P. 
Ibs. 

Duration  

9  5 

Weight  of  feed-water  consumed    
Feed-water  consumed  per  hour     
Pressure  in  steam  pipe  above  atmosphere  
Pressure  in  receiver  above  atmosphere  (not  verified)    . 
Vacuum  in  condenser 

.     .  216,002.45 
.     .     22,737.1 
.     .           151.5 
.     .             11.8 
26  8 

Revolutions  per  minute 

75  18 

Mean  effective  pressure,  H.  P.  cylinder      ..... 

.     .            61.76 
15  53 

Mean  effective  pressure,  L   P   cylinder 

Indicated  horse-power,  H.  P.  cylinder 

848  27 

Indicated  horse-power,  L.  P.  cylinder  
Indicated  horse-power,  whole  engine     
Feed-water  consumed  per  I.  H.  P.  per  hour    .... 

.     .          865.58 
.     .       1,713.85 
.     .            13.27 

Measurements  based  on  Sample  Diagrams. 


H.P. 
CYLINDER. 

L.  P. 
CYLINDER. 

Initial  pressure  above  atmosphere  . 
Corresponding  steam-pipe  or  receiver 
pressure    

Ibs. 
Ibs 

1430 
151  0 

15.5 
*11  8 

Cut-off  pressure  above  zero    .... 
Release  pressure  above  zero  .... 
Mean  effective  pressure      
Back  pressure  at  mid  stroke  above  or 
below  atmosphere  . 

Ibs. 
Ibs. 
Ibs. 

Ibs 

152.3 
44.4 

61.53 

+  20  0 

22.0 
9.5 

15.84 

—  11  5 

Proportion  of  stroke  completed  at  cut- 
off   

326 

421 

Steam  accounted  for  at  cut-off    .     .     . 
Steam  accounted  for  at  release  . 
Proportion  of  feed-water  accounted  for 
at  cut-off 

Ibs. 
Ibs. 

10.84 
10.84 

817 

10.98 
10.85 

828 

Proportion  of  feed-water  accounted  for 
at  release  ....                    .' 

817 

818 

*  Not  verified. 
221 


222  ENGINE    TESTS. 

Engine  No.  55  is  a  cross  compound  with  horizontal  un- 
jacketed  cylinders  and  a  reheating  receiver.  The  steam  is 
exhausted  into  a  surface  condenser  operated  by  an  independent 
steam-driven  air  and  circulating  pump.  The  quantity  of  steam 
used  by  the  condenser  was  determined  independently  and 
allowed  for.  The  steam  is  taken  from  vertical  water-tube 
boilers  in  a  slightly  superheated  state.  The  valves  and  pistons 
of  both  cylinders  were  found  to  be  in  excellent  condition 
throughout,  with  practically  no  leakage.  The  load  was  an 
electric  generator  located  on  the  main  shaft,  furnishing  current 
for  motors  in  a  cotton  mill.  The  steam  condensed  in  the  re- 
heater  coil  amounted  to  three  and  one  half  per  cent  of  the  total 
weight  of  steam  passing  the  throttle  valve.  This  is  included 
in  the  quantities  given  in  the  table. 

A  noticeable  feature  in  these  results  is  the  close  agreement 
between  the  four  quantities  given  for  steam  accounted  for  by 
the  indicator.  Three  of  these  are  practically  equal,  and  the 
fourth  differs  only  one  per  cent. 


ENGINE  No.55 


140- 

120- 

100- 

80- 

60- 

40- 

20- 

0- 


H.P.  Head  End 


H.P.  Crank  End 


-140 

—  120 
-100 

-  80 

-  60 
-40 

—  20 

—  0 


L.P.  Head  End 


—  !6 

-  10 

—  5 

-  0 

—  5 

-  10 


L.P.  Crank  End 


i-  15 

—  10 

-  5 

-  0 

—  5 

-  10 


ENGINE   No.  56. 


Compound  Condensing  Engine. 


H.P. 
CYLINDER. 

L.  P. 
CYLINDER. 

Kind  of  engine          

Four  valv 

1 
22| 

4i 

3.5 
3 

.0799 
1 
Some 
leakage 

e  (Corliss) 
1 
42 
J4i 
[« 
3.5 
4 

.2897 
3.63 
Some 
leakage 

Number  of  cylinders      ...... 
Diameter  of  cylinder     ins. 

Diameter  of  piston  rod                                 ins 

Stroke  of  piston  ft. 
Clearance   ....                    .                   % 

H.  P.  constant  for  1  Ib.  in.  e.  p.  one 
revolution  per  minute    .     .     .     .  H.P. 
Ratio  of  areas  of  cylinders     .... 
Condition  of  valves  and  pistons  regard- 
ing leakage   

Data  and  Results  of  Feed -Water  Test. 

Character  of  steam       ,..-.... 

Duration 5.0 

Weight  of  feed-water  consumed     .     .     .     .     .     >.     .  ,  .    -.     .  60,636 
Feed- water  consumed  per  hour 12,127.3 


Pressure  in  steam  pipe  above  atmosphere 
Pressure  in  receiver  above  atmosphere  . 
Vacuum  in  condenser  .  .  .  .  .  . 

Revolutions  per  minute 

Mean  effective  pressure,  H.  P.  cylinder  . 
Mean  effective  pressure,  L.  P.  cylinder  .  . 
Indicated  horse-power,  H.  P.  cylinder  .  . 
Indicated  horse-power,  L.  P.  cylinder  .  . 
Indicated  horse-power,  whole  engine  .•  . 
Feed-water  consumed  per  I.  H.  P.  per  hour 


107.8 
11.0 
25.2 
120.2 
45.07 
11.30 
432.93 
394.12 
827.05 
14.67 


Ordinary 

hrs. 

Ibs. 

Ibs. 

Ibs. 

Ibs. 

ins. 

rev. 

Ibs. 

Ibs. 
H.P. 
H.P. 
H.P. 

Ibs. 


Measurements  based  on  Sample  Diagrams. 


H.  P. 
CYLINDER. 

L.  P. 
CYLINDER. 

Initial  pressure  above  atmosphere  . 

Ibs. 

102.2 

11.1 

Corresponding  steam-pipe  and  receiver 

pressure    .  •_  .     .  .  ' 

Ibs. 

107.0 

11.0 

Cut-off  pressure  above  zero    .     .'    .     ." 

Ibs. 

99.0 

20.3 

Release  pressure  above  zero    .     .     /  . 

Ibs. 

36.0 

8.5 

Mean  effective  pressure      .     .     .     .     .. 

Ibs. 

44.93 

11.29 

Back  pressure  at  mid  stroke  above  or 

below  atmosphere  

Ibs. 

+11.6 

-10.5 

Proportion  of  stroke  completed  at  cut-off 

.331 

.362 

Steam  accounted  for  at  cut-off   .     .     .  ' 

Ibs. 

11.87 

10.46 

Steam  accounted  for  at  release  .     .     . 

Ibs. 

12.91 

11.79 

Proportion  of  feed-water  accounted  for 

at  cut-off                           .... 

.813 

.716 

Proportion    of    feed-water    accounted 

for  at  release      

.88 

.806 

224 


ENGINE  No.    56.  225 

Engine  No.  56  is  a  tandem  compound  with  horizontal  jack- 
eted cylinders  and  reheating  receiver.  Steam  is  supplied  to 
the  bottom  of  each  cylinder,  and  the  jacket  spaces  form  a 
thoroughfare  through  which  it  passes  to  the  steam  chest  at  the 
top.  The  jackets  are  drained  by  traps  which  discharge  to 
waste.  A  jet  condenser  is  used,  with  an  independent  steam- 
driven  air-pump,  which  is  supplied  from  an  independent  boiler. 
Steam  is  taken  from  horizontal  return  tubular  boilers,  and 
it  contained  0.8  °]0  of  moisture  at  a  point  near  the  throttle 
valve.  The  valves  and  pistons  were  found  to  be  in  fair  condi- 
tion, but  not  the  best.  The  load  consisted  of  an  electric  gene- 
rator placed  on  the  driving-shaft,  which  for  the  test  supplied 
current  to  a  water  rheostat. 

This  is  an  example  of  a  Corliss  engine  running  at  compara- 
tively high  rotative  speed  and  piston  speed  as  well,  which  is  gen- 
erally considered  to  be  one  of  the  conditions  which  contribute 
to  good  economy.  The  result,  however,  is  nothing  unusual. 
The  conclusion  cannot  fairly  be  drawn  from  this  test  that  such 
a  speed  produces  no  advantage  ;  for  there  were  other  conditions 
pertaining  to  the  work,  such  as  the  pressure  and  vacuum,  which 
were  unfavorable  to  economy. 


ENGINE  No.56 


100- 
80— 
60- 
40- 
20- 
0- 


H.P.  Head  End 


H.P.  Crank  End 


100 

80 

60 

-40 

-20 

-    0 


L.P.  Head  End 


L.P.  Crank  End 


ENGINE    No.  57. 

Compound  Condensing  Engine. 


H.  P. 

CYLINDER. 

L.  P. 

CYLINDER. 

Kind  of  engine     .          

Four  valv< 
1 

28 

5 
2.6 

.1844 

1 

Practica 

3  (Corliss) 
1 
56 
6 
5 
3.7 

.7425 
4.03 

lly  tight 

Number  of  cylinders      

Diameter  of  cylinder     ins. 
Diameter  of  piston  rod       ins. 
Stroke  of  piston  ft. 
Clearance                                                          % 

Horse-power  constant  for  one  Ib.  in.e.p. 
one  revolution  per  minute    .     .     .H.P. 
Ratio  of  areas  of  cylinders     .... 
Condition  of  valves  and  pistons  regard- 
ing leakage   

Data  and  Results  of  Feed  -  Water  Test. 


Character  of  steam      

.     .     .                Ordinary 

Duration  

...            5.0 

hrs. 

Weight  of  feed-water  consumed     

.     .     .  94,545. 

Ibs. 

Feed-water  consumed  per  hour      

.     .     .   18,909. 

Ibs. 

Pressure  in  steam  pipe  above  atmosphere    .... 

.     .     .        133.00 

Ibs. 

Pressure  in  receiver  above  atmosphere    .     .     .     .     . 

.     .     .          13.60 

Ibs. 

Vacuum  in  condenser       

...          25.20 

ins. 

Revolutions  per  minute    

.     .     .          66.04 

rev. 

Mean  effective  pressure,  H.  P.  cylinder       .     ... 

.     .     .          52.27 

Ibs. 

Mean  effective  pressure,  L.  P.  cylinder  

.     .     .          14.37 

Ibs. 

Indicated  horse-power,  H.  P.  cylinder              .     .     . 

.     .     .    '•  636.61 

H.P. 

Indicated  horse-power,  L.  P.  cylinder     .     .     .     .     ." 

.     .     .        704.64 

H.P. 

Indicated  horse-power,  whole  engine      

.     .     .      1341.25 

H.P. 

Feed-water  consumed  per  I.  H.  P.  per  hour     .     .     . 

.     .     .,         14.10 

Ibs. 

Measurements  Based  on  Sample  Diagrams. 


H.P. 
CYLINDER. 

L.  P. 
CYLINDER. 

Initial  pressure  above  atmosphere  .     .     Ibs. 

125.2 

139 

Corresponding  steam-pipe  and  receiver 

pressure    Ibs. 

133.0 

13.1 

Cut-off  pressure  above  zero    ....     Ibs. 

121.3 

20.8 

Release  pressure  above  zero  ....     Ibs. 

38.9 

10.1 

Mean  effective  pressure      Ibs. 

51.87 

14.5 

Back  pressure  at  mid  stroke  above  or 

below  atmosphere  Ibs. 

+16.3 

-11.4 

Proportion  of  stroke  completed  at  cut-off 

.294 

.429 

Steam  accounted  for  at  cut-off    .     .     .     Ibs. 

982 

11.22 

Steam  accounted  for  at  release   .     .     .     Ibs. 

10.34 

11.57 

Proportion  of  feed-water  accounted  for 

at  cut-off  

.696 

.796 

Proportion  of  feed-water  accounted  for 

at  release 

.733 

.821 

228  ENGINE    TESTS. 

Engine  No.  57  is  a  cross  compound  with  unjacketed  horizon- 
tal cylinders  and  a  reheating  receiver.  The  condenser  is  of 
the  siphon  type,  the  water  for  which  is  supplied  by  an  inde- 
pendent steam  pump  which  takes  steam  from  the  main  pipe 
and  exhausts  into  the  receiver.  Steam  is  furnished  by  vertical 
water-tube  boilers  in  a  slightly  superheated  condition.  The 
load  was  cotton  machinery.  The  leakage  tests  showed  that  the 
valves  and  pistons  were  all  in  excellent  condition  throughout, 
excepting  the  exhaust  valve  at  the  crank  end  of  the  low-pres- 
sure cylinder,  which  leaked  a  considerable  amount. 

A  test  was  made  of  the  steam  consumed  by  the  condenser 
pump  when  exhausting  into  the  condenser;  and  it  was  found 
that  it  used,  under  these  circumstances,  1,176  Ibs.  per  hour,  or 
.9  of  a  pound  per  I.  H.  P.  per  hour.  When  exhausting  into 
the  receiver,  as  it  did  on  the  test,  the  consumption  was  consid- 
erably greater ;  but  a  large  proportion  of  it  was  utilized  by 
increasing  the  power  developed  in  the  low-pressure  cylinder. 
It  is  estimated  that  .5  of  a  pound  per  I.  H.  P.  per  hour  is 
chargeable  to  the  condenser  pump  when  used  as  it  was  on  the 
main  test.  The  effect  of  exhausting  the  pump  into  the  receiver 
in  this  way  is  indicated  in  the  analysis  of  the  diagrams,  which 
shows  a  considerably  larger  amount  of  steam  accounted  for 
in  the  low-pressure  cylinder  than  that  shown  in  the  H.  P. 
cylinder. 


ENGINE  No.  57 


H.P.  Crank  End 


—120 
-100 
-80 

—  60 

—  40 
-20 
-    0 


L.P.  Head  End 


—  15 

-  10 

—  5 

—  0 

—  5 

-  10 


L.P.  Crank  End 


-  16 

-  10 

—  6 

—  0 
5 

-  10 


ENGINE    No.  58, 


Compound  Condensing  Engine. 


H.  P. 
CYLINDER. 

L.  P. 
CYLINDER. 

Kind,  of  engine 

ins. 
ins. 
ft. 

% 

H.P. 

Four  valv 
1 
26 
5 
4 
4 

.1269 
1 
Practically 
tight 

e  (Corliss) 
1 
50 
5.5 
4 
4.8 

.4719 
3.72 
Practically 
tight 

Number  of  cylinders     
Diameter  of  cylinder     
Diameter  of  piston  rod       

Stroke  of  piston  
Clearance    

H.  P.  constant  for  one  Ib.  m.  e.  p.,  one 
revolution  per  minute      .... 
Katio  of  areas  of  cylinders     .... 
Condition  of  valves  and  pistons  regard- 
ing leakage    

Data  and  Results  of  Feed -Water  Tests. 


TEST  LOAD. 

A. 

CONSTANT. 

B. 
VARIABLE. 

Character  of  steam  

Ordinary 

Ordinary 

Duration     ..........     hrs. 

2.5 

3.0 

Weight  of  feed-water  consumed       .     .     Ibs. 

34,040.0 

34,239.0 

Feed-water  consumed  per  hour  .     .     .     Ibs. 

13,616.0 

11,413.0 

Pressure  in  steam  pipe  above  atmos.    .     Ibs. 

136.2 

128.9 

Pressure  in  receiver  above  atmosphere    Ibs. 

16.8 

12.8 

Vacuum  in  condenser   ins. 

26.2 

26.2 

Revolutions  per  minute      

78.0 

78.0 

Mean  effective  pressure,  H.  P.  cylinder  Ibs. 

*47.38 

Mean  effective  pressure,  L.  P.  cylinder  Ibs. 

*15.24 

Indicated  horse-power,  H.  P.  cylinder   H.P. 

*468.97 

Indicated  horse-power,  L.  P.  cylinder   H.P. 

*560.19 

Indicated  horse-power,  whole  engine    .  H.P. 

1,030.06 

843.44 

Feed-water  consumed  per  I.  H.P.  per  hr.    Ibs. 

13.21 

13.53 

Measurements  based  on  Sample  Diagrams,  Test  A. 


H.  P. 
CYLINDER. 

L.  P. 
CYLINDER. 

Initial  pressure  above  atmosphere  .     . 
Corresponding  steam-pipe  and  receiver 
pressure  ^  .     .     . 
Cut-off  pressure  above  aero-  d^r*0.     .•' 
Release  pressure  above  zero  .     .     ... 
Mean  effective  pressure     .                    i 

Ibs. 

Ibs. 
Ibs. 
Ibs. 
Ibs 

131.9 

136.0 
120.7 
37.9 
47  85 

18.2 

1(5.7 

OJEX)   I* 
O 

15.17 

Back  pressure  at  mid  stroke,  above  or 
below  atmosphere  

Ibs 

+  21.2 

—  12.8 

Proportion  of  stroke  completed  at  cut-off 
Steam  accounted  for  at  cut-off    .     .     . 
Steam  accounted  for  at  release    .     . 
Proportion  of  feed-water  accounted  for 

Ibs. 
Ibs. 

.293 
10.56 
10.92 

.8 

.274 

9.48 
9.69 

.718 

Proportion  of  feed-water  accounted  for 
at  release                                .     . 

.826 

.733 

230 


ENGINE  No.  58.  231 

Engine  No.  58  is  a  cross  compound  with  horizontal  un- 
jacketed  cylinders  and  a  reheating  receiver.  The  condenser  is 
of  the  jet  type  with  an  independent  steam  driven  air-pump,  the 
quantity  of  steam  used  by  which  was  determined  and  allowed 
for.  The  steam  is  taken  from  water-tube  boilers,  and  at  the 
throttle  valve  was  found  to  contain  .2  of  one  per  cent  of  mois- 
ture. The  load  was  an  electric  generator  carried  by  the  fly- 
wheel shaft,  and  on  Test  "  A  "  the  current  was  consumed  in  a 
water  rheostat,  while  that  of  Test  "  B  "  was  used  by  the  motors 
of  an  electric  street  railroad,  and  the  load  was  variable.  The 
valves  and  pistons  were  in  an  unusually  tight  condition 
throughout. 

The  weight  of  steam  condensed  in  the  reheater  coil  on 
test  "A"  was  500  Ibs.  per  hour,  or  about  .5  of  a  pound  per 
I.  H.  P.  per  hour;  and  this  is  included  in  the  quantities  given 
in  the  tables^  In  th^  diagrams  which  are  appended  for  the 
variable  load  test,  the  two  extreme  lines  are  reproduced  which 
were  taken  for  a  period  covering  ten  consecutive  revolutions. 
During  the  wh^Le  trial  with  variable  load,  the  maximum  varia- 
tion of  the  load  was  shown  by  the  extreme  readings  of  the 
ammeter.  The  highest  was  1,456  amperes  and  the  lowest  624. 
The  next  highest  readings  were  1,300  amperes,  and  the  next 
lowest  669. 

*  These  figures  were  determined  from  ten  sets  of  diagrams,  the  average 
horse-power  developed  by  the  whole  engine  being  1029.16.  The  average 
horse-power  used  for  working  up  the  results  (1030.6)  was  determined  from  the 
average  electrical  readings,  using  the  efficiency  corresponding  to  the  readings 
when  the  ten  sets  were  obtained.  On  the  variable  load  test  the  horse-power 
was  determined  from  the  electrical  readings  by  using  the  average  efficiency 
found  by  independent  tests  made  with  a  steady  load,  this  load  being  the  average 
load  of  the  main  trial. 


ENGINE  No.  58a 


120- 

100 
80- 
60- 
40- 
20- 
0- 


H.P.  Head  End 


H.P.  Crank  End 


-120 
—100 

—  80 

—  60 

—  40 

—  20 

—  0 


L.P.  Head  End 


-20 

-  15 

-  10 

-  6 

-  0 
—  6 

-  10 


L.P.  Crank  End 


-20 

—  15 
-10 

—  5 

—  0 

—  5 

—  10 


ENGINE  No.58b 


120- 
100- 
80- 
60- 
40- 
20- 
0- 


H.P.  Head  End 


H.P.  Crank  End 


—120 
-100 

—  80 

—  60 
—40 

—  20 
-    0 


L.P.  Head  End 


20 

15 
10 
-  5 
0 
5 
10 


L.P.  Crank  End 


20 
15 
10 
5 
0 
5 
10 


TRIPLE  EXPANSION 


235 


ENGINE    No.  59. 


Triple  Expansion  Engine. 


H.P. 
CYLINDER. 

TNT. 
CYLINDER. 

L.  P. 
CYLINDER. 

Kind  of  engine 

Four 

valve  (Co 

rliss) 

Number  of  cylinders 

1 

2 

Diameter  of  cylinders   ...          .     .     ins. 

20 

34 

36 

Diameter  of  piston  rod       ins. 

4| 

41 

Stroke  of  piston  ft. 

5 

5 

I  6 
5 

Clearance    % 

2.5 

2.5 

2.5 

H.  P.  Constant  for  one  Ib.  in.e.p.,  one 

rev.  per  minute       II.  P. 

.0928 

.2727 

.3017  each 

Ratio  of  areas  of  cylinders     .... 

1 

2.94 

6.5  twc 

Condition  of  valves  and  pistons  regard- 

Consid. 

Practic'ly 

Practic'ly 

ing  leakage    

leakage 

tight 

tight 

Data  and  Results  of  Feed  -Water  Test. 

Character  of  steam 

Duration 

Wei giit  of  feed-water  consumed 

Feed-water  consumed  per  hour 

Pressure  in  steam  pipe  above  atmosphere 

Pressure  in  first  receiver  above  atmosphere 

Pressure  in  second  receiver  above  atmosphere 

Vacuum  in  condensers 

Revolutions  per  minute 

Mean  effective  pressure,  H.  P.  cylinder 

Mean  effective  pressure,  intermediate  cylinder     .     .     . 

Mean  effective  pressure,  L.  P.  cylinder .    . 

Indicated  horse-power,  H.  P.  cylinder , 

Indicated  horse-power,  intermediate  cylinder  .....     ( 

Indicated  horse-power,  L.  P.  cylinder 

Indicated  horse-power,  whole  engine .  , 

Feed-water  consumed  per  I.  H.  P.  per  hour 

Measurements  Based  on  Sample  Diagrams. 


.    Superheated  39° 
10.375      hrs. 
131,461 
.   12,670.9 
151 
33 
4 

'.          27 

65.24 

59.59 

13.19 

10.19 
360.9 
234.7 
401.2 
996.8 

12.71 


Ibs. 
Ibs. 
Ibs. 
Ibs. 
Ibs. 
ins. 

Ibs. 
Ibs. 


H.P. 
H.P. 
H.P. 
H.P. 

Ibs. 


.. 

H.P. 
CYLINDER. 

INT. 
CYLINDER. 

L.  P. 
CYLINDER. 

Initial  pressure  above  atmosphere    .     .     Ibs. 

142. 

32.9 

4.1 

Corresp.  steam-pipe  pressure      .     .     .      Ibs. 

152. 

Cut-off  pressure  above  zero    ....     Ibs. 

145.2 

38.7 

16 

Release  pressure  above  zero  ....     Ibs. 

53. 

17.4 

6.7 

Mean  effective  pressure     .     .     .     .           Ibs. 

60.56 

13.22 

10.16 

Back  pressure  at  mid  stroke  above  or 

below  atmosphere       Ibs. 

+32.6 

+4.8 

-12.5 

Proportion  of  stroke  completed  at  cut-off 

.346 

.406 

.357 

Steam  accounted  for  at  cut-off    .     .     .     Ibs. 

9.81 

9.53 

8.39 

Steam  accounted  for  at  release   .     .     .     Ibs. 

10.42 

10.45 

9.95 

Proportion  of  feed-water  accounted  for 

at  cut-off  .... 

.773 

.741 

.66 

Proportion  of  feed-water  accounted  for 

at  release       

.82 

.822 

.783 

238  ENGINE    TESTS. 

Engine  No.  59  is  a  horizontal  four-cylinder  engine,  arranged 
in  the  manner  of  a  pair  of  tandem  compound  engines.  The 
cylinders  nearest  the  beds  are  the  low-pressure  cylinders,  of 
which  there  are  two.  The  high-pressure  cylinder  is  in  front 
of  one  of  the  low-pressure  cylinders,  and  the  intermediate 
cylinder  in  front  of  the  other.  The  cylinders  are  jacketed  on 
the  system  which  allows  the  steam  which  is  supplied  to  the 
cylinder  to  first  pass  through  the  jacket  space,  each  jacket  thus 
being  filled  with  steam  having  the  initial  pressure  of  supply. 
The  jackets  are  drained  into  receivers,  and  these  are  provided 
with  pumps  operated  by  the  engine.  They  discharge  the 
water  into  reheaters  placed  in  the  flue  of  the  boilers.  The 
steam  which  is  formed  in  the  reheaters  is  supplied  to  the  re- 
ceiver between  the  intermediate  and  the  low-pressure  cylinders. 
This  receiver  is  provided  with  a  coil  of  live  steam  pipe  pre- 
senting 33  square  feet  of  exterior  surface.  The  total  quantity 
of  water  condensed  in  the  jackets  and  withdrawn  from  them 
amounted  to  691  Ibs.  per  hour,  or  about  5  %  of  the  total  quan- 
tity of  steam  supplied  to  the  engine.  About  one-half  of  this 
was  re-evaporated  in  the  re  heater  and  utilized  in  the  low- 
pressure  cylinders.  The  condensers,  of  which  there  are  two, 
are  of  the  jet  type,  and  operated  by  direct  connected  air-pumps. 
Steam  is  supplied  from  vertical  tubular  boilers,  and  on  the  test 
it  was  superheated  39°  at  a  point  near  the  boilers.  With  the 
exception  of  the  high-pressure  piston,  which  leaked  quite  badly, 
the  valves  and  pistons  were  all  in  a  practically  tight  condition. 

The  load  on  the  engine  consisted  of  cotton  machinery.  The 
loss  of  steam  which,  referring  to  the  analysis  of  the  diagrams, 
took  place  between  the  intermediate  cylinder  and  the  low-pres- 
sure cylinders  is  noticeable  in  view  of  the  arrangements  made 
to  reheat  the  steam  in  the  receiver,  and  augment  the  supply 
by  means  of  the  jacket-water  re-evaporated  in  the  flue  heaters. 
It  shows  the  powerful  action  of  cylinder  condensation,  and  the 
necessity  of  employing  more  efficient  means  for  overcoming 
the  loss. 


ENGINE  No.  59 


H.P.  Head  End 


140- 
120- 
100- 
80- 
60- 
40- 
20- 
0- 


-140 
120 
100 

-  80 

-  60 
-40 

20 

-  0 


H.P.  Crank  End 


Intm  Head  End 


40-, 
30- 
20- 
10- 

o- 


Intm  Crank  End 


40 
30 
20 
10 
0 


LNGINE  No.  59 


R.H.L.P.  Head  End 


-  0 

-  6 

-  10 

-15 


R.H.L.P.  Crank  End 


0- 

6— 
10- 
15- 


L.H.L.P.  Head  End 


5- 
0- 
6- 
10- 
15- 


L.H.L.P.  Crank  End 


-  5 

-  0 

-  5 
-10 
-15 


ENGINE  No.  60. 


Triple  Expansion  Engine. 


H.  P. 
CYL. 

INT.  CYL. 

L.  P. 
CYL. 

Kind  of  engine  .-..,. 
Number  of  cylinders                                  *     . 

Four 

1 
28 
two  4 
5 
1.4 
1 
Fairly 
tight 

valve  (Co 
1 
48 
two  4 
5 
1.5 
2.98 
Fairly 
tight 

rliss) 
1 
74 
two  4 
5 
.8 
7.11 
Fairly 
tight 

Diameter  of  cylinder  ins. 
Diameter  of  piston  rod    .     ins. 
Stroke  of  piston                                     .                ft. 

Clearance      % 

Ratio  of  areas  of  cylinders  
Condition  of  valves  and  pistons  regarding 
leakage 

Data  and  Results  of  Feed- Water  Test. 
Character  of  steam    .     .     .     ,     .     ...     .     •."  .  .     . 
Duration      .     .     .     .     .     ...     .     ,     .     .     .     .     . 

Weight  of  feed-water  consumed 

Feed-water  consumed  per  hour 

Pressure  in  steam  pipe  above  atmosphere 

Pressure  in  first  receiver  above  atmosphere 

Pressure  in  second  receiver  above  atmosphere 

Vacuum  in  condenser    ....     .     . 

Revolutions  per  minute 

Mean  effective  pressure,  H.  P.  cylinder 

Mean  effective  pressure,  intermediate  cylinder 

Mean  effective  pressure,  L.  P.  cylinder     .     .     ...     .     .     . 

Indicated  horse-power,   H.  P.  cylinder      ........ 

Indicated  horse-power,  intermediate  cylinder     .     .     . 
Indicated  horse-power,  L.  P.  cylinder  .     .     .     .     .     .     .     . 

Indicated  horse-power,  whole  engine 

Feed -water  consumed  per  I.  H.  P.  per  hour  .     .     .,    . 

Measurements  based  on  Sample  Diagrams. 


Ordinary 


72.0 

hrs. 

518,811.0 

Ibs. 

7,205.7 

Ibs. 

125.6 

Ibs. 

30.3 

Ibs. 

IKo 

25.3 

IDS. 

ins. 

20.99 

rev. 

49.85 

Ibs. 

15.4 

Ibs. 

7.57 

Ibs. 

191.3 

H.P. 

176.04 

H.P. 

206.39 

H.P. 

573.73 

H.P. 

12.55 

Ibs. 

H.P. 
CYL. 

INT. 
CYL. 

L.  P. 
CYL. 

Initial  pressure  above  atmosphere     .     .     .     Ibs. 
Corresponding    steam-pipe    and    receiver 
pressure     Ibs. 
Cut-off  pressure  above  zero      .     .     .     .     .     Ibs. 
Release  pressure  above  zero     .....     Ibs. 
Mean  effective  pressure                                      Ibs 

124.3 

129.7 
134.1 
44.7 

50  07 

30.4 

30.1 
30.3 
14.3 
15  41 

0.2 

1.0 
11.5 

5.8 
7  59 

Back  pressure  at  mid  stroke,  above  or  be- 
low atmosphere  Ibs. 
Proportion  of  stroke  completed  at  cut-off  . 
Steam  accounted  for  at  cut-off      ....     Ibs. 
Steam  accounted  for  at  release     ....     Ibs. 
Proportion  of  feed-water  accounted  for  at 
cut-off    

+29.4 
.338 
9.48 
9.96 

.756 

0.0 
.362 
9.53 

9.97 

.759 

-11.9 
.479 
9.45 
9.91 

.753 

Proportion  of  feed-water  accounted  for  at 
release        ....     

.793 

.794 

.789 

241 


242  ENGINE    TESTS. 

Engine  No.  60  is  a  vertical  triple  expansion  pumping-engine 
with  jacketed  cylinders  and  two  reheaters.  Only  the  barrels 
of  the  cylinders  are  jacketed,  the  heads  being  unjacketed,  ex- 
cept so  far  as  the  valve  chests,  which  are  located  in  the  heads, 
furnish  a  substitute.  The  jacket  of  the  low-pressure  cylinder 
is  supplied  with  steam  at  a  reduced  pressure.  The  remaining 
jackets  and  the  reheaters  are  supplied  with  boiler  steam.  The 
engine  is  furnished  with  steam  from  horizontal  return  tubular 
boilers,  and  at  a  point  near  the  throttle  valve  the  percentage  of 
moisture  was  found  to  be  .3  %.  There  was  no  undue  leakage 
of  the  valves  and  pistons,  but  they  were  not  in  a  perfectly  tight 
condition.  The  load  of  each  cylinder  is  that  of  a  direct-acting 
pump,  the  diameter  of  each  plunger  being  36,  "  and  the  total 
head,  expressed  in  pounds,  53.4  Ibs.  per  square  inch.  The 
jackets  consumed  955  Ibs.  of  steam  per  hour,  which  is  12.7  %  of 
total  used  by  the  engine ;  and  this  is  included  in  the  quantities 
given  in  the  tables.  When  the  engine  was  at  rest,  the  jackets 
consumed  163.5  Ibs.  per  hour,  being  the  loss  due  to  radiation. 

The  analysis  of  the  diagrams  in  this  test  shows  a  remarkably 
close  agreement  between  the  steam  accounted  for  by  the  indi- 
cator in  the  various  cylinders.  There  is  a  variation  of  less  than 
1  °f0  between  the  quantities  shown  at  the  cut-off  in  the  three 
cylinders,  and  a  similarly  close  agreement  in  the  three  quanti- 
ties shown  at  the  release. 


120- 
100 
80- 
GO- 
40- 
20- 
0- 


ENGINENo.  60 


H.P.Top 


H.P    Bottom 


r!20 
100 
-80 
-60 
^40 
-20 
0 


Intl^Top 


-30 

-20 

10 

-  0 


-30 
-20 
-10 

-  o 


ENGINE  No.  6O 


L.P.  Top 


o- 

4- 
8- 
12- 


L.P.  Bottom 


r—  0 

-4 
-  0 
-12 


SUMMARY   OF  FEED -WATER    TESTS. 


245 


(0 
0) 

k. 

o 

4-» 

03 


o    s 


246 


ENGINE    TESTS. 


cc  o  ©  a    I-H  I-H  ©  <M  !>  <M  o  t    as  o  I-H  co  o  od  i—  i  o  10 

OICOTtti—  lCOCOCCCCS<ICC(7<ICOi—  !5<|i7vJI>-<J<ICCO7'3^S<l 


N<Nl--5;liCQOr-(O;OS<l?OClQOOiO 
-^'<- 


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CO  CO  CD  'M  "-O  to  Ci  O  O  O  O  " 

I-H  T-I  i-HCCCCCO 


LEAKAGE 
CONDITIONS 


COO         ii3  1-1  i—  i  O  CO 


<N  1-1  T-  i  -^  00 


a>       a? 

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SUMMARY   OF  FEED -WATER    TESTS. 


247 


r-  1  <N  t~  T*  i—  lOOiO>—  I 


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CONDITI 


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248 


ENGINE    TESTS. 


fe          J 


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CONDITI 


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i-*0©i-i<X<NOaOO<MO<Nt~ 


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REVIEW   OF    FEED -WATER  TESTS. 


249 


REVIEW    OF   FEED -WATER    TESTS. 


IT  could  hardly  be  expected  that  conclusive  information  upon 
the  subjects  which  are  of  most  interest  in  connection  with  the 
operation  of  steam  engines  could  be  obtained  from  a  large  num- 
ber of  tests  made  on  engines  of  various  sizes,  running  under 
different  conditions  of  service,  and  located  in  plants  which  are 
not  always  best  adapted  for  experimental  purposes  or  research, 
like  the  tests  under  consideration.  Such  tests,  however,  cannot 
but  bring  out  some  points  on  these  subjects  which  are  of  consid- 
erable practical  value,  if  for  no  other  reason  than  that  the  tests 
were,  in  the  main,  conducted  under  those  very  circumstances  of 
practical  operation  which  alone  could  give  results  of  that  nature. 

The  tests  furnish  information  in  regard  to  cylinder  condensa- 
tion, leakage  of  valves  and  pistons,  the  effect  of  pressure  and 
speed,  the  economy  of  condensing  and  superheating,  the  relative 
economy  of  simple,  compound,  and  triple  expansion  engines,  the 
effect  of  steam  jacketting  and  reheating,  the  effect  of  different 
ratios  of  cylinder  areas  in  compound  engines,  and  some  miscel- 
laneous questions ;  and  these  are  discussed  in  the  order  named. 

I.     CYLINDER    CONDENSATION    AND    LEAKAGE. 

Cylinder  condensation  and  leakage  is  that  part  of  the  feed- 
water  consumption  which  is  not  accounted  for  by  the  indicator 
diagram.  It  is  necessary  to  put  these  two  losses  in  one  class^ 
There  is  no  way  of  separating  them  either  absolutely  or  ap- 
proximately. The  only  practicable  thing  to  do  is  to  test  the 
valves  and  pistons  for  leakage  with  the  engine  at  rest ;  and  if 
under  these  conditions  they  prove  to  be  tight,  it  is  fair  to  as- 
sume that  the  leakage  under  conditions  of  running  is  practically 
nothing,  and  the  part  not  accounted  for  by  the  diagram  is 
wholly  or  substantially  cylinder  condensation.  If  a  similar 
engine,  working  under  similar  conditions,  is  found  by  such  tests 

251 


252 


ENGINE    TESTS. 


to  leak,  and  then  a  comparison  is  made  between  the  loss  in  the 
tight  engine  and  that  in  the  leaking  engine,  an  inference  can  be 
drawn  as  to  the  extent  of  the  leakage  and  how  much  the  loss 
amounts  to  in  percentage  of  the  whole  consumption.  Practi- 
cally, it  may  be  said  that  it  is  unnecessary  to  know  the  absolute 
amount  of  cylinder  condensation,  for  it  is  seldom  that  an  engine 
is  found  in  an  absolutely  tight  condition ;  and,  after  all,  the  im- 
portant thing  to  know  is  what  the  cylinder  condensation  and 
leakage  amount  to  when  the  engine  is  in  ordinarily  good  work- 
ing condition.  These  tests  furnish  satisfactory  evidence  on  this 
point,  especially  those  made  on  simple  engines.  Selection  may 
properly  be  made  from  the  list  of  simple  engines,  those  of  the 
larger  sizes  of  the  four-valve  type,  using  ordinary  steam,  taking 
those  which  are  tight  or  leaking  only  a  small  amount ;  namely, 
those  numbered  1,  2,  3,  5,  6,  7,  17,  18,  20,  22,  25,  28,  29,  30, 
and  31.  These  are  tabulated  as  follows,  being  arranged  in  the 
order  of  the  point  of  cut-off :  — 


No.  OF 
ENGINE. 

CUT-OFF. 

PROPORTION 
OF  FEED- 
WATER 
ACCOUNTED 

FOR  AT 

CUT-OFF. 

CYLINDER 
CONDENSA- 
TION AND 
LEAKAGE. 

31  A 

.041 

.382 

.618 

31  C 

.084 

.509 

.491 

18  B 

.111 

.668 

.332 

31  D 

.121 

.588 

.412 

20  A 

.119 

.615 

.385 

3A. 

.138 

.654 

.346 

30 

.139 

.645 

.355 

3B 

.160 

.695 

.305 

22 

.172 

.669 

.331 

31  C 

.178 

.709 

.291 

18  A 

.188 

.725 

.275 

29 

.194 

679 

.321 

20  B 

.222 

.722 

.278 

31  F 

.231 

.745 

.255 

7 

.237 

.750 

.250 

25 

.243 

.737 

.263 

6 

.252 

.757 

.243 

17  A 

.264 

.770 

.230 

28 

.271 

.781 

.219 

5 

.303 

.784 

.216 

2 

.315 

.817 

.183 

31  B 

.323 

.796 

.204 

1  A 

.367 

.840 

.160 

1  B 

.375 

.839 

.161 

17  B 

.385 

.820 

.180 

REVIEW   OF  FEED -WATER    TESTS.  253 

These  proportions  of  cylinder  condensation  and  leakage  can 
better  be  examined  by  referring  to  the  accompanying  chart  on 
which  they  are  plotted,  ordinates  or  verticals  representing  per- 
centages of  cut-off,  and  abscissae  or  horizontals,  percentages  of 
condensation  and  leakage.  The  curved  line  drawn  through 
them  represents  the  mean  curve  of  condensation  and  leakage 
deduced  from  these  results.  It  clearly  shows  that  the  percent- 
age rapidly  increases  as  the  point  of  cut-off  becomes  earlier, 
and  at  the  very  earliest  cut-off  the  condensation  and  leakage 
bears  a  very  large  proportion  to  the  total  consumption  of 
steam. 

The  best  series  of  tests  on  this  subject,  using  the  same 
engine,  are  those  made  on  Engine  No.  31,  which  was  a  pair  of 
Corliss  non-condensing  engines  having  cylinders  16  in.  diameter 
and  42  in.  stroke.  This  engine  was  practically  tight,  and  the 
percentages  of  condensation  (and  leakage)  over  a  range  of  cut- 
off  from  4%  to  32%  was  from  62%  down  to  20%. 

That  leakage  has  an  important  effect  upon  the  economy  of 
an  engine  is  well  shown  by  a  comparison  of  the  results  obtained 
from  engines  which  leaked  excessively  with  those  shown  on 
the  chart.  For  example,  in  Engine  No.  19,  which  is  of  the 
single-valve  type  showing  considerable  leakage  compared  with 
Corliss  engines,  the  proportion  of  steam  accounted  for  is  .706 
at  30%  cut-off,  giving  condensation  and  leakage  of  29.4%. 
The  condensation  and  leakage  shown  on  the  average  curve  of 
the  chart  at  that  cut-off  is  about  20%,  so  that  the  difference 
between  20  and  29.4  must  be  due  in  a  laige  degree  to  leakage. 
In  Engine  No.  26  a  test  with  a  leaking  exhaust  valve  showed 
condensation  and  leakage  of  30.8%.  When  the  valve  had  been 
repaired  and  made  tight,  the  condensation  and  leakage  dropped 
down  to  25.5%,  the  difference  being  due  almost  entirely  to  a 
reduction  in  leakage.  The  saving  in  actual  feed-water  con- 
sumption was  about  10%. 

In  the  compound  engine  tests  which  can  be  compared  for  the 
purpose  of  studying  cylinder  condensation,  the  range  of  cut- 
off in  the  high-pressure  cylinder  is  hardly  sufficient  to  serve 
as  a  basis  for  satisfactory  conclusions.  The  tests  which  can  be 


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REVIEW   OF  FEED-WATER    TESTS. 


255 


fairly  compared  for  this  purpose  are  those  numbered  32,  34,  36, 
49,  53,  55,  56,  and  5 8 A.  The  range  of  cut-off  in  the  high- 
pressure  cylinder  is  from  .238  to  .331,  and  the  range  of  steam 
accounted  for  at  cutoff  in  the  same  cylinder  is  from  .717  to 
.866.  These  are  tabulated  below: 


PROPORTION  OF 

NO.  OF 

ENGINE. 

CUT-OFF, 
H.  P.  CYL. 

FEED-WATER 
ACCOUNTED  FOR 
AT  CUT-OFF, 

H.  P.  CYL. 

32 

.305 

.774 

36 

.295 

.767 

49 

.330 

.866 

53 

.238 

.717 

55 

.326 

.817 

56 

.331 

.813 

58  A 

.293 

.800 

Average, 

.303 

.793 

The  average  cylinder  condensation  and  leakage  in  these 
cases  is  100-79.3  =  20.7%,  and  the  average  cut-off  in  the  high- 
pressure  cylinder  is  .303.  If  these  be  compared  with  the 
curve  of  condensation  and  leakage  given  on  the  chart  for  the 
simple  engines,  it  will  be  seen  that  this  average  falls  closely 
upon  that  curve.  The  point  on  the  curve  for  30%  cut-off  is 
20.5%.  The  engines  selected  are  those  in  which  the  high-pres- 
sure cylinder  is  unjacketed,  or  of  the  class  in  which  the  jacket 
space  forms  a  thoroughfare  through  which  steam  is  supplied 
to  the  chest.  It  may  be  inferred  from  the  close  agreement  be- 
tween the  average  of  these  tests  and  the  indications  of  simple 
engines  in  the  matter,  that  the  curve  of  condensation  and  leak- 
age for  simple  engines  applies  also  to  the  high-pressure  cylinder 
of  compound  engines  where  these  are  unjacketed,  and  where 
the  valves  and  pistons  are  fairly  tight. 

Condensation  and  leakage  in  the  low-pressure  cylinder  of  the 
compound  engines  reported  above  is  affected  to  a  considerable 
extent  by  the  conditions  regarding  jacketing  and  reheating, 
Where  there  is  neither  jacketing  nor  reheating,  the  conden- 


256 


ENGINE    TESTS. 


sation  and  leakage  is  much  greater  in  the  low-pressure  cylinder 
than  in  the  H.  P.  cylinder.  For  example,  reference  may  be  made 
to  Engines  No.  32,  36,  46A,  47A,  48B,  52D,  and  53,  in  which 
the  proportions  of  cylinder  condensation  and  leakage  are  as 
follows : 


CONDENSATION 

CONDENSATION 

No.  OF 

AND  LEAKAGE 

AND  LEAKAGE 

ENGINE. 

CUT-OFF 

CUT-OFF, 

H.  P.  CYL. 

L.  P.  CYL. 

32 

.226 

.28 

36 

.233 

.36 

46  A 

.194 

.29 

47  A 

.212 

.32 

48  B 

.144 

.26 

52  D 

.266 

.35 

53 

.283 

.40 

Average, 

.222 

.323 

The  average  of  these  shows  10%  more  condensation  and 
leakage  in  the  L.  P.  cylinder  than  in  the  H.  P.  cylinder. 

That  leakage  in  itself  produces  an  important  effect  in  com- 
pound engines  is  exhibited  in  the  case  of  one  engine  reported, 
that  of  No.  38,  where  the  feed-water  consumption  per  I.  H.  P. 
per  hour  is  19.36  Ibs.  The  leakage  here  was  in  the  low-pres- 
sure piston  ;  and  although  the  cylinders  of  the  engine  were  jack- 
eted, and  the  receiver  also  jacketed,  the  condensation  and 
leakage  at  cut>off  in  the  H.  P.  cylinder  was  32.5%  against 
17.5%  by  the  simple-engine  curve,  and  57.0%  at  cut-off  in  the 
L.  P.  cylinder;  the  increase  between  the  two  cylinders  being 
24.5%. 

If  we  may  judge  from  indications  of  one  test,  that  of  Engine 
No.  26,  the  effect  of  leakage  upon  the  consumption  of  steam 
and  economy  of  the  engine  may  be  exceedingly  marked,  and  at 
the  same  time  have  so  little  influence  upon  the  lines  of  the 
diagram  that  it  may  be  scarcely  noticeable.  In  this  instance, 
the  form  and  position  of  the  expansion  line  with  reference  to  a 
hyperbolic  curve  drawn  through  the  cut-off  point  of  the  diagram 
is  so  nearly  the  same  that  careful  measurements  would  hardly 


REVIEW   OF  FEED -WATER    TESTS.  257 

distinguish  a  difference,  although  in  one  case  the  exhaust 
valve  leaked  no  less  than  10%.  Practically  the  same  effect,  or 
rather  want  of  effect,  has  been  noticed  in  one  other  case  where 
a  broken  packing-ring  in  a  piston  caused  a  leakage  which 
amounted  to  a  still  larger  quantity.  A  close  examination  of 
the  expansion  line  of  the  diagrams,  before  and  after,  failed  to 
reveal  any  clearly  denned  difference.  This  is  Engine  No.  78. 
In  a  case  like  that  of  the  compound  Engine  No.  38,  it  cannot 
be  inferred  from  this  that  the  influence  of  excessive  leakage 
could  not  be  revealed  by  a  study  of  the  indicator  diagrams. 
Here  it  did  produce  a  marked  effect  in  the  distribution  of  the 
load  between  the  cylinders,  cutting  down  the  power  developed 
in  the  L.  P.  cylinder,  and  increasing  it  to  a  corresponding  ex- 
tent in  the  H.  P.  cylinder.  At  the  same  time,  it  caused  a 
noticeable  "  drop  "  in  pressure  at  the  high-pressure  release. 

In  studying  the  effect  of  cylinder  condensation  and  leakage, 
and  the  extent  of  the  loss  which  it  produces,  the  quantity 
shown  at  the  cut-off  point  of  the  diagram  is  selected  in  prefer- 
ence to  that  shown  at  the  release,  in  the  belief  that  at  the  cut- 
off point  the  full  extent  of  the  loss  is  the  more  truthfully 
indicated.  If  the  steam  accounted  for  at  both  points  is  identi- 
cal, the  loss  is  the  same  at  one  point  as  at  the  other,  and  it  does 
not  matter  which  point  is  selected.  If  the  quantity  accounted 
for  is  larger  at  the  release  than  it  is  at  the  cut-off,  which  owing 
to  re-evaporation  during  expansion  frequently  occurs,  the  appar- 
ent loss  due  to  condensation  and  leakage  is  less  at  the  release 
than  it  is  at  the  cut-off.  Sometimes  there  is  as  much  as  10  per 
cent  less  apparent  condensation  and  leakage  at  the  release 
than  at  the  cut-off.  In  cases  like  this  the  release  percentage 
does  not  show  the  full  extent  of  loss,  because  the  work  recov- 
ered on  account  of  re-evaporation  is  in  no  sense  proportional  to 
the  increase  in  the  steam  accounted  for  at  that  point.  Neither 
does  the  loss  at  cut-off  in  such  cases  represent  the  true  loss, 
and  the  reason  is  the  same ;  but  the  loss  at  cut-off  furnishes  a 
closer  indication  of  the  true  loss  than  the  loss  at  release,  and 
a  better  basis  for  the  study  of  the  question  of  cylinder  conden- 
sation. 


258  ENGINE   TESTS. 

It  will  be  noticed  in  the  table  giving  the  quantities  upon 
which  the  chart  of  cylinder  condensation  and  leakage  is  based, 
that  no  distinction  is  made  between  engines  which  are  condens- 
ing and  those  running  non-condensing.  It  is  probable  that  the 
transfer  of  heat  from  the  steam  to  the  metal  of  the  cylinder, 
under  the  action  of  the  comparatively  low  temperature  of  the 
condenser,  is  different  from  that  which  occurs  in  the  non-con- 
densing engine ;  and  if  a  suitable  investigation  were  made,  this 
difference  would  appear  in  the  percentage  of  cylinder  conden- 
sation. Whatever  this  difference  may  be,  it  is  not  sufficiently 
marked  to  be  noticeable  in  the  tests  referred  to  in  the  chart; 
and  consequently  the  results  are  used  indiscriminately,  whether 
the  engines  are  condensing  or  non-condensing. 


II.    EFFECT    OF    PRESSURE    ON    THE    ECONOMY. 

Other  things  being  the  same,  it  is  a  well  recognized  princi- 
ple in  steam-engineering  that  the  higher  the  pressure  the  more 
economical  the  consumption  of  steam.  But  circumstances 
attending  its  use  are  not  always  the  same  ;  and  consequently, 
in  examining  the  results  obtained  from  different  engines,  such 
as  those  here  reported,  it  does  not  follow  that  in  any  individ- 
ual case  where  the  pressure  is  highest  the  economy  is  necessarily 
the  greatest.  For  example,  two  tests  are  reported  on  Engine 
No.  18,  which  show  practically  the  same  economy  as  measured 
by  the  feed-water  consumed  per  I.  H.  P.  per  hour ;  yet  the 
pressure  in  one  case  is  84  Ibs.,  and  in  the  other  case  59  Ibs.  It 
is  evident  that  the  difference  in  the  cut-off  which  accompanied 
the  change  of  pressure  exerted  such  an  influence  that  the 
benefit  which  might  have  been  derived  from  a  higher  pressure 
was  counterbalanced. 

There  are  two  instances  among  the  simple  engines  which 
may  be  examined  to  show  the  importance  due  to  increased 
pressure.  Test  No.  1  A  and  test  No.  2  is  one  of  these  in- 
stances. Here  an  increase  of  the  pressure  from  72.3  Ibs.  to 
101  Ibs.,  accompanied  by  a  slight  shortening  of  the  cui>off,  had 
a  marked  effect  in  improving  the  economy,  the  consumption  of 


REVIEW    OF  FEED -WATER    TESTS.  259 

feed-water  being  reduced  from  27.8  Ibs.  to  25.8  Ibs.  Another 
comparison  may  be  made  between  test  No.  7  and  test  No. 
31  F.  Here,  with  the  same  cut-off,  an  increase  of  pressure 
from  80.5  Ibs.  to  98.6  Ibs.  was  evidently  the  principal  cause  of 
a  reduction  in  the  consumption  from  29.03  Ibs.  per  I.  H.  P.  per 
hour  to  25.31  Ibs. 

In  the  list  of  the  compound  engines,  there  are  two  tests 
which  can  be  compared  for  this  purpose,  —  those  numbered  32 
and  36.  In  No.  32,  with  a  pressure  of  94.8  Ibs.,  and  the  cut- 
off in  the  high  pressure  cylinder  .305,  the  feed-water  consump- 
tion is  16.28  Ibs.  per  I.  H.  P.  per  hour.  In  test  No.  36,  with 
126.8  Ibs.  pressure,  and  the  cut-off  at  .295,  or  practically  the 
same  as  in  the  other  case,  the  consumption  is  reduced  to 
14.05  Ibs. 

That  an  increased  pressure  in  the  same  engine  is  advanta- 
geous under  some  circumstances,  is  clearly  shown  by  test  48  A 
and  48  C.  In  the  latter  the  pressure  was  100.2  Ibs.,  and  the 
consumption  of  feed-water  15.08  Ibs.,  while  in  the  former  the 
pressure  was  125,9  Ibs.,  and  with  practically  the  same  load,  the 
consumption  was  14.12  Ibs.  In  this  case  the  benefit  due  to 
the  increase  of  pressure  was  largely  enhanced  by  the  increased 
expansion  obtained,  the  cut-off  in  the  H.  P.  cylinder  dropping 
from  .432  to  .294. 

III.     EFFECT    OF    SPEED    UPON    ECONOMY. 

The  speeds,  expressed  in  revolutions  per  minute,  vary  in 
these  tests  from  a  minimum  of  21  to  a  maximum  of  356.7. 
With  such  a  wide  range,  there  is  reason  for  expecting  informa- 
tion as  to  the  economy  to  be  derived  from  increasing  the 
rotative  speed,  but  the  tests  furnish  no  conclusive  evidence  on 
this  subject.  The  high-speed  engines  are  all,  or  nearly  all,  of  a 
different  class  from  the  low-speed  ones,  and  the  nature  of  the 
design  and  construction  is  such  that  certain  features  which  are 
necessary  for  the  highest  economy  are  sacrificed  in  order  to 
obtain  the  desired  increase  of  speed.  Many  of  the  high-speed 
engines  have  a  single  valve  which  performs  all  the  functions  of 
the  four  valves  in  a  slow-speed  engine.  The  result  is  that 


260  ENGINE    TESTS. 

these  functions  are  not  so  perfectly  performed  in  the  engines 
which  run  at  high  speed,  and  there  is  a  loss  of  economy. 
Furthermore,  the  valves  in  the  high-speed  engines  are  generally 
of  some  balanced  type  ;  and  valves  of  this  kind  are  not  so  well 
adapted  to  tight  construction,  and  do  not  maintain  so  tight  a 
condition  as  those  of  the  four  valves  in  slow-speed  engines. 
Again,  the  high-speed  engines  usually  require  larger  clearance 
spaces  in  the  cylinders  than  those  of  the  slow-speed  class.  For 
these  various  reasons,  the  high-speed  engine  is  handicapped  at 
the  outset  with  conditions  which  are  unfavorable  to  economy  ; 
and  if  the  effect  of  the  high  speed  is  advantageous,  the 
advantage  must  be  so  great  as  to  overcome  the  losses  noted  if  it 
is  to  show  in  favor  of  the  high-speed  engine  when  it  is  sub- 
jected to  a  test.  An  examination  of  the  tests  reported,  taking 
those  engines  which  are  run  at  the  highest  speeds,  shows,  that 
in  every  case  they  are  less  economical  than  the  slow-speed 
engines,  and  in  every  case  the  reason  appears  in  one  or  more  of 
the  points  mentioned.  There  is  a  further  reason  for  the  com- 
paratively low  economy  of  the  high-speed  engines  reported,  in 
the  fact  that  in  almost  all  cases  the  engines  given  are  of  com- 
paratively small  size  ;  and  this,  no  doubt,  has  an  important 
influence  in  making  the  engine  less  economical  than  it  would 
otherwise  be. 

There  is  one  case  given  where  a  Corliss  engine  was  run  at  a 
speed  of  one  hundred  and  twenty  revolutions  per  minute,  —  that 
of  Engine  No.  56 ;  and  this  may  be  compared  with  the  other 
Corliss  engines  running  a  lower  speed.  The  comparison,  how- 
ever, is  not  a  very  satisfactory  one  ;  because  the  valves  and 
pistons  were  not  in  the  best  condition  in  regard  to  leakage,  and 
the  boiler  pressure  was  rather  lower  than  that  obtained  on  other 
engines  with  which  it  could  be  compared.  Looking  at  the 
proportion  of  steam  accounted  for  by  the  indicator,  which  is 
.813,  there  is  nothing  in  this  indication  to  show  any  marked 
improvement  due  to  the  high  rotative  speed,  if  such  existed. 


REVIEW   OF  FEED -WATER 


IV.     ECONOMY    OF    CONDENSING. 

It  is  held,  in  the  popular  mind,  that  the  economy  of  con- 
densing is,  in  round  numbers,  25%.  This  percentage  usually 
relates  to  simple  engines,  and  it  refers  to  the  economy  as  meas- 
ured by  the  difference  in  the  coal  consumption  produced  by 
a  condenser.  The  evidence  of  some  of  the  tests  here  given 
shows  that  this  belief  is  not  well  founded,  unless  it  be  in 
special  cases.  The  economy  due  to  condensing  ought  to  be 
reckoned  on  the  basis  of  coal  consumption,  and  not  alone  on 
the  basis  of  feed- water  consumption  ;  because  a  non-condensing 
engine  is  usually  accompanied  by  a  feed- water  heater,  and  some 
of  the  loss  of  economy  produced  by  running  non-condensing  is 
made  up  by  the  saving  of  coal  due  to  warming  the  feed-water. 
If  the  feed-water  is  heated  by  the  exhaust  steam  of  the  non-con- 
densing engine  from  a  temperature  of  100°,  which  is  that  of  the 
ordinary  hot  well,  to  a  temperature  of  210°,  the  non-condensing 
engine  can  be  credited  with  about  11%  less  coal  consumption. 
This  matter  should  properly  be  taken  into  account  when  con- 
sidering the  economy  produced  by  a  condenser. 

In  the  list  of  simple  engines,  a  number  of  comparisons  are 
made  on  the  same  engine  when  carrying  the  same  load,  one 
test  being  made  with  the  engine  condensing  and  the  other 
non-condensing.  In  the  case  of  Engine  No.  10,  where  such  a 
comparison  was  made,  the  feed- water  consumed  when  running 
non-condensing  was  25.64  Ibs.  per  I.  H.  P.  per  hour,  and  when 
running  condensing,  20.51  Ibs.,  the  difference  being  5.13  Ibs., 
or  20%  of  the  larger  quantity.  In  Engine  No.  17,  which 
was  tried  in  the  same  manner,  the  consumption  running  non- 
condensing  was  28.93  Ibs.,  and  condensing,  22.08  Ibs.,  the 
difference  being  6.85,  or  24%  of  the  larger  quantity.  In 
Engine  No.  20,  a  similar  test  was  made ;  and  the  consumption 
in  one  case  was  30.16  Ibs.,  and  in  the  other  23  Ibs.,  the  dif- 
ference being  7.16  Ibs.,  or  24%  of  the  larger  quantity.  The 
average  of  these  three  comparisons  gives  a  saving  produced 
by  condensing  of  22.3%.  If  we  allow  for  the  steam  or  power 
used  by  an  economical  condenser,  it  wrill  be  seen  that  the  net 


262  ENGINE    TESTS. 

economy  of  condensing  is,  at  best,  not  much  over  20%  ; 
and  this  is  on  the  basis  of  steam  consumption.  If,  further- 
more, we  allow  for  the  difference  produced  by  heating  the 
feed- water  to  the  extent  mentioned  above,  the  saving  of  fuel 
would  be  reduced  to  about  11%.  In  some  cases  in  practice 
where  these  conditions  exist,  the  difference  in  favor  of  con- 
densing might  be  greater,  owing  to  the  evaporative  economy 
of  the  boilers  being  improved  by  reducing  the  work  upon 
them ;  but  all  that  could  be  fairly  expected  on  the  basis  of 
these  three  engines,  other  things  being  the  same,  would  be  not 
much  over  10%. 

There  is  another  method  of  looking  at  this  subject ;  and  that 
is,  to  compare  the  best  performance  of  engines  running  con- 
densing with  the  best  results  running  non-condensing.  The 
best  non-condensing  result,  in  the  list  of  simple  engines  using 
ordinary  steam,  is  that  of  Engine  No.  31  F,  working  at  about 
100  Ibs.  pressure  at  .231  cut-off,  and  developing  287.1  indi- 
cated horse-power.  This  result  is  25.39  Ibs.  The  best  result 
obtained  from  a  condensing  engine,  using  ordinary  steam,  is 
that  of  No.  22,  working  at  a  pressure  of  82.3  Ibs.  at  .172 
cut-off,  the  engine  developing  613.4  I.  H.  P.  This  is  18.49 
Ibs.  per  I.  H.  P.  per  hour.  Comparing  these  two  figures,  there 
is  a  difference  in  favor  of  the  condensing  engine  of  6.9  Ibs., 
or  27.2%  of  the  larger  quantity.  Allowing  for  steam  or 
power  used  by  the  condensing  apparatus,  the  net  economy 
in  feed-water  consumption  is  not,  at  best,  over  25%  ;  and  fur- 
ther allowance  for  the  gain  due  to  heating  the  feed-water,  as 
estimated  in  the  former  case,  would  bring  the  coal-saving  down 
to  about  17%.  It  appears,  therefore,  that  the  tests  here  given 
on  simple  engines  do  not  confirm  the  popular  impression  that 
the  saving  produced  by  condensing  is  25%. 

The  economy  of  condensing,  as  compared  with  non-con- 
densing, depends  to  some  extent  on  the  type  of  air-pump  and 
condenser  employed.  There  are  four  principal  classes  of 
these :  — 

1.  The  jet  condenser  and  direct-connected  air-pump,  which 
uses  power  supplied  by  the  main  engine. 


REVIEW   OF  FEED-WATER    TEtfTS.  263 

2.  The  siphon  type  of  condenser,  in  which  the  water  is  sup- 
plied by  gravity,  and  no  air-pump  is  required. 

3.  The  siphon  condenser,  in  which  the  water  is  supplied  by 
an  independent  pump. 

4.  The  jet  condenser,  with  air-pump  driven  by  an  indepen- 
dent engine  or  other  motor. 

In  all  of  these,  with  the  exception  of  the  second,  the  expen- 
diture of  power  or  the  consumption  of  steam  must  be  charged 
against  the  saving  due  to  condensing.  Those  that  use  steam 
can  be  arranged  to  utilize  a  portion  of  that  steam  in  cases 
where  the  exhaust  from  the  independent  engine  or  pump  is 
carried  through  a  feed-water  heater,  and  the  heat  returned  to 
the  boiler.  In  test  No.  15,  which  was  provided  with  a  jet 
condenser  and  directrconnected  air-pump,  the  amount  of  power 
used  by  the  air-pump  was  found  to  be  1.8%  of  the  working 
power  of  the  engine.  In  Engine  No.  57,  which  was  pro- 
vided with  a  siphon  condenser  supplied  with  water  by  an 
independent  pump,  the  quantity  of  steam  used  by  the  pump, 
when  exhausting  into  the  condenser,  was  6.7%  of  the  total 
consumption  of  steam  by  the  engine.  In  Engine  No.  19, 
which  was  provided  with  a  jet  condenser  operated  by  an  in- 
dependent steam-driven  air-pump,  the  consumption  of  steam 
by  the  pump  when  exhausting  into  the  air  was  13%  of  the 
total  quantity  used  by  the  engine.  In  Engine  No.  20,  which 
was  fitted  with  a  similar  condenser,  the  quantity  of  steam 
used  by  the  air-pump  when  exhausting  into  the  condenser 
was  over  13%  of  the  total  quantity.  When  an  independent 
steam-driven  air-pump  is  used,  and  the  heat  of  the  exhaust 
steam  is  returned  to  the  boilers  so  far  as  possible  by  heating 
the  feed-water,  it  is  probable  that  from  one-half  to  two-thirds 
of  the  steam  is  saved ;  and  in  a  case  where  the  air-pump  uses 
12%  of  the  entire  quantity,  the  actual  loss  of  coal  due 
to  the  air-pump  would  be  not  over  4  or  5%.  From  these 
considerations  it  appears  that  in  cases  where  an  air-pump 
or  other  condenser  pump  is  required,  the  percentage  to  be 
charged  to  the  condenser  on  this  account  is,  in  the  best  in- 
stances, about  2%  ;  and  in  cases  where  the  exhaust  steam 


264  ENGINE    TESTS. 

from  the  motor  is  not  properly  utilized,  it  may  be  so  great 
as  to  largely  offset  the  economy  otherwise  resulting  from  the 
use  of  the  condenser. 

The  tests  furnish  some  data  as  to  the  economy  produced  by 
a  condenser  in  compound  engines.  In  Engine  No.  33,  with 
practically  the  same  load,  the  use  of  the  condenser  reduced 
the  consumption  of  steam  per  I.  H.  P.  per  hour  from  22.53 
Ibs.  to  18.92  Ibs.,  or  16%.  In  Engine  No.  45,  the  use  of 
the  condenser,  with  a  nearly  "constant  load,  reduced  the  con- 
sumption from  23.24  Ibs.  to  16.07  Ibs.,  or  31%.  A  compari- 
son may  be  made  between  Engines  41  and  42.  The  latter 
(42  B),  running  non-condensing,  used  25.2  Ibs.  per  I.  H.  P. 
per  hour ;  and  the  former  (41  B),  running  condensing,  used 
19.1  Ibs.  The  reduction  due  to  condensing  here  is  24%. 
Engine  No.  46,  which  is  run  non-condensing,  may  be  com- 
pared with  Engine  No.  48,  which  is  run  condensing,  making 
allowance  for  the  difference  in  the  condition  of  the  steam. 
In  this  instance  the  condenser  appears  to  have  reduced  the 
feed- water  consumption  about  30%.  In  all  these  no  account 
is  taken  of  the  steam  used  by  the  condensing  apparatus,  the 
percentages  given  being  the  gross  savings.  Throwing  out  En- 
gine No.  33,  w^hich  may  be  regarded  as  of  special  design,  and 
possibly  not  useful  for  general  comparison,  it  appears  that  the 
effect  of  the  condenser  on  the  compound  engines  is  considerably 
greater  than  in  the  case  of  the  simple  engines.  It  will  be  seen, 
however,  that  the  advantage  of  the  condenser  in  compound 
engines  depends  largely  upon  the  boiler  pressure ;  and  a  com- 
parison made  on  an  engine  like  No.  41,  which  is  running  at  130 
Ibs.,  would  show  very  differently  from  what  it  would  in  an  en- 
gine like  No.  54,  for  example,  which  is  run  at  167  Ibs.  The 
effect  of  the  vacuum  on  the  low-pressure  cylinder  is  much  more 
telling  when  the  boiler  pressure  is  low,  and  less  work  is  done 
in  the  high-pressure  cylinder,  than  it  is  when  the  boiler  pressure 
is  high. 

At  pressures  ranging  between  120  and  140  Ibs.,  it  would 
appear  from  these  records  that  a  4-valve  compound  engine  run- 
ning non-condensing  would  use  not  over  21.5  Ibs.  of  feed- water 


REVIEW   OF  FEED-WATER    TESTS.  265 

per  I.  H.  P.  per  hour ;  and  a  similar  engine  running  condensing, 
with  the  usual  proportions  of  cylinders,  would  use  not  over 
14  Ibs.  The  difference  between  the  two  is  7.5  Ibs.,  or  about 
35%  in  favor  of  the  condensing  engine.  Allowing,  say,  2% 
for  power  used  by  a  direct-connected  air-pump,  and  making 
further  allowance,  as  in  the  case  of  the  simple  engines  men- 
tioned, for  the  effect  of  a  feed-water  heater,  the  net  saving  of 
fuel  in  favor  of  the  condensing  engine  is  about  25%. 

The  effect  on  a  pair  of  condensing  engines  produced  by  run- 
ning one  end  of  one  cylinder  non-condensing  is  shown  in  two 
cases.  In  Engine  No.  3  the  effect  was  to  increase  the  consump- 
tion of  feed-water  from  21.11  Ibs.  to  22.68  Ibs.,  or  about  1%. 
In  Engine  No.  9  the  increased  consumption  amounted  to 
about  12%.  The  object  of  running  an  engine  in  this  man- 
ner is  to  utilize  a  portion  of  the  steam  for  heating  the  feed- 
water,  or  for  other  uses  to  which  exhaust  steam  can  be  adapted. 
If  its  use  is  confined  to  heating  feed-water,  and  the  amount  is 
110°,  or  that  corresponding  to  the  instances  heretofore  noted, 
an  advantage  would  be  produced,  provided  the  increased  con- 
sumption did  not  exceed  11%.  If  in  these  two  engines  the 
exhaust  steam  from  the  single  end  were  used  for  that  pur- 
pose, there  would  be  a  net  gain  corresponding  to  about  7% 
in  Engine  No.  3,  and  a  net  loss  corresponding  to  1%  in 
Engine  No.  9. 

V.     EFFECT    OF    SUPERHEATING. 

The  effect  which  superheating  has  upon  the  economy  of  an 
engine  is  clearly  shown  in  the  case  of  Engine  No.  1,  where  test 
No.  1  C  was  made  with  the  steam  superheated  82°,  and  test 
No.  1  B  under  practically  the  same  conditions,  except  that  the 
steam  was  practically  dry.  This  was  a  simple  non-condens- 
ing engine.  The  economy  produced  by  the  superheating  was 
sufficient  to  reduce  the  feed-water  consumption  from  29.34 
Ibs.,  per  I.  H.  P.  per  hour,  to  26.83  Ibs.,  or  8.6%  or  about 
1%  for  each  10°  of  superheating.  This  may  be  examined  fur- 
ther by  comparing  this  and  other  simple  engines  which  use 
superheated  steam  with  those  using  ordinary  steam.  The  effect 


266 


ENGINE    TESTS. 


can  best  be  studied  by  comparing  the  cylinder  condensation  and 
leakage,  in  the  case  of  the  engines  using  superheated  steam, 
with  the  curve  of  condensation  and  leakage  given  on  the  chart 
for  simple  engines  using  ordinary  steam.  For  example,  in  the 
case  of  test  No.  1  C  the  cut-off  is  .392,  the  proportion  of  feed- 
water  accounted  for  at  cut-off  .947,  and  the  cylinder  conden- 
sation and  leakage  5.3%.  On  the  curve  for  ordinary  steam 
referred  to,  the  condensation  and  leakage  at  a  cut-off  of  .392 
is  16.7%.  The  difference  between  5.3  and  16.7,  which  is 
11.4%,  represents  the  reduction  in  the  condensation  due  to 
the  superheating,  as  determined  by  this  method  of  comparison. 
Pursuing  the  matter  in  the  same  way  for  the  remaining 
engines,  we  have  the  following  table : 


CYLINDER 

No. 

DEGREES 

OF 

SUPER- 
HEATING. 

CUT-OFF. 

PROPOR- 
TION OF 
FEED- 
WATER 
ACCOUNTED 

FOR   AT 

CUT-OFF. 

PROPOR- 
TION OF 
CYLINDER 
CONDENSA- 
TION AND 
LEAKAGE. 

CONDENSA- 
TION AND 
LEAKAGE 

DERIVED 
FROM 

CURVE  FOR 
ORDINARY 

PROPOR- 
TION RE- 
DUCED BY 
SUPER- 
HEATING. 

STEAM. 

1  C 

82 

.392 

.947 

.053 

.167 

.114 

4 

25 

.233 

.766 

.234 

.255 

.021 

8  A 

37 

.247 

.819 

.181 

.243 

.062 

8  B 

37 

.165 

.747 

.253 

.334 

.081 

9  A 

24 

.18S 

.820 

.180 

.307 

.127 

9B 

24 

.225 

.836 

.164 

.261 

.097 

15 

59 

.281 

.895 

.105 

.215 

.110 

Average, 

41° 

.087 

From  this  comparison  it  appears  that  with  steam  superheated 
41°  (generally  at  a  point  near  the  boilers,  and  a  considerable 
distance  from  the  engine),  the  proportion  of  condensation  and 
leakage  was  reduced  an  average  of  8.7%.  Assuming  as  a 
criterion  the  relation  between  the  actual  saving  in  the  case  of 
No.  1  Engine,  and  the  reduced  proportion  of  cylinder  condensa- 
tion, which  was  about  .8,  this  reduction  in  the  cylinder  con- 
densation corresponds  to  an  actual  saving  of  feed- water  of  7%. 
Assuming  that  if  the  engines  had  been  supplied  with  ordinary 


EEVIEW   OF  FEED- WATER    TESTS.  267 

steam,  this  steam  would  have  contained  1%  of  moisture,  cor- 
responding in  round  numbers  to,  say,  20°  of  superheating, 
the  difference  in  the  quality  of  the  steam  in  the  two  cases, 
expressed  as  superheating,  is  about  60°.  According  to  this 
calculation,  therefore,  the  effect  of  the  superheating  is  to  re- 
duce the  feed-water  consumption  7%  for  a  superheating  of 
60°,  or  a  trifle  over  1%  for  each  10°;  and  this  practically 
corroborates  the  evidence  furnished  by  the  tests  on  Engine 
No.  1. 

The  compound  engine  which  shows  the  highest  economy  of 
any  in  the  list,  is  one  which  is  supplied  with  superheated  steam  ; 
and  although  this  fact  may  be  considered  as  one  reason  for 
the  high  result,  there  were  other  conditions  which  were  favor- 
able, and  the  exact  effect  of  the  superheating  is  a  matter  of 
conjecture. 

Incidentally,  it  should  be  noted  that  superheating  produces 
a  marked  effect  in  the  character  of  the  expansion  line  of  the 
indicator  diagram.  In  Engine  No.  1  this  is  clearly  revealed  by 
a  comparison  of  the  steam  accounted  for  by  the  indicator  at 
cut-off  and  release.  In  test  No.  1  B,  where  the  engine  was 
running  with  ordinary  steam,  the  proportion  accounted  for  at 
cut-off  is  .839,  and  that  at  release  is  .861,  which  is  an  increase 
of  .022.  On  the  other  hand,  on  test  No.  1  C,  where  the  steam 
was  superheated  82°,  the  proportion  accounted  for  at  cut-off 
was  .947,  and  at  release  .900,  there  being  a  reduction  here 
of  .047.  This  change  is  evidently  due  to  the  reduced  con- 
densation produced  by  the  superheating,  and  the  consequent 
reduction  in  the  amount  of  re-evaporation  during  expansion. 


VI.     RELATIVE   ECONOMY    OF    SIMPLE,  COMPOUND     AND    TRIPLE 
EXPANSION    ENGINES. 

In  comparing  the  economy  of  a  compound  or  other  multiple 
expansion  engine  with  that  of  a  simple  engine,  the  question  may 
be  raised,  What  should  be  the  conditions  of  the  comparison  ? 
One  method  of  comparing  the  two  would  be  to  select  those  run- 
ning under  the  same  boiler  pressure  and  quality  of  steam,  and 


268  ENGINE    TESTS. 

with  similar  provisions  in  regard  to  jacketing.  This  method 
may  be  interesting  and  valuable  for  scientific  research  ;  but  for 
practically  showing  the  advantages  of  compound  engines,  it  is  of 
little  importance,  because  one  of  the  principal  objects  in  com- 
pounding is  to  enable  the  economy  due  to  large  expansions  and 
high  pressures  to  be  obtained  without  the  sacrifice  which  such 
expansions  produce  when  carried  on  during  the  single  stage 
which  occurs  in  one  cylinder.  The  nearest  approach  to  a  com- 
parison of  this  kind,  derived  from  the  tests  reported,  is  that  of 
compound  Engine  No.  32,  which  was  made  with  a  boiler  pres- 
sure of  94.8  Ibs.  Here  the  engine  was  unjacketed,  and  no 
provision  was  made  for  re-heating  between  the  cylinders.  If 
we  compare  this  with  the  very  best  result  obtained  from  a 
simple  condensing  engine,  that  of  No.  22,  there  appears,  even 
under  these  circumstances,  a  marked  difference  in  favor  of  the 
compound  engine.  These  figures  are  18.49  for  the  simple 
engine,  and  16.28  for  the  compound;  and  the  difference  is  2.21 
Ibs.,  or  about  12%.  Comparing  this,  again,  with  simple  Engine 
No.  28,  which  is  running  at  70  Ibs.  pressure  on  a  consumption 
of  19.45  Ibs.  of  feed-water  per  I.  H.  P.  per  hour,  the  difference 
is  3.17  Ibs.,  or  16.3%. 

A  fairly  satisfactory  comparison  between  compound  engines 
and  simple  engines,  where  no  jacketing  or  re-heating  is  pro- 
vided, can  be  made  by  using  compound  Engine  No.  36.  This 
engine  was  jacketed  ;  but  the  jackets  were  not  drained,  and 
consequently,  under  the  circumstances,  they  were  ineffective. 
In  this  engine  the  consumption  of  feed-water  was  14.05  Ibs. 
per  I.  H.  P.  per  hour  when  running  at  a  pressure  of  106.8  Ibs. 
If  we  compare  this  with  No.  28,  simple  engine,  the  difference 
is  5.4  Ibs.,  or  27.8%. 

A  general  comparison  between  the  compound  and  simple 
engines  may  be  made  without  regard  to  the  matter  of  pressure 
or  the  use  of  jackets  and  re-heaters,  and  without  regard  to  the 
quality  of  the  steam,  omitting  the  three  engines  which  have  an 
excessively  high  ratio  of  cylinder  areas.  The  engines  selected 
are  those  of  the  Corliss  or  other  4-valve  type.  Such  a  compari- 
son is  made  in  the  following  tables. 


REVIEW   OF  FEED- WATER    TESTS. 
Simple  Condensing  Engines. 


269 


NUMBER. 

FEED-WATER  CONSUMED 
PER  I.  H.  P.  PER  HOUR. 

3  A 

21.11 

8  A 

19.39 

8  B 

18.71 

9  A 

18.25 

18  A 

20.31 

18  B 

20.56 

22 

.       18.49 

28 

19.45 

30 

21.42 

Average, 

19.74 

Compound  Condensing  Engines. 


NUMBER. 

FEED-WATER  CONSUMED 
PER  I.  H.  P.  PER  HOUR. 

32 

16.28 

34 

13  28 

36 

14.05 

37 

13.37 

43 

13.26 

48  A 

14.12 

48  B 

14.01 

48  C 

15.08 

49 

14.18 

50 

13.28 

53 

15.78 

55 

13.27 

56 

14.60 

57 

14.10 

58  A 

13.21 

Average, 

14.12 

The  average  of  the  results  on  the  simple  condensing  engines 
is  19.74  Ibs.,  and  of  those  on  the  compound  condensing  engines, 
14.12  Ibs.  The  difference  is  5.62  Ibs.,  or  28.5%  of  the  feed- 
water  consumption  of  the  simple  engines. 

In  the  case  of  non-condensing  compound  engines  of  the 
4-valve  type,  there  is  only  one  engine  in  this  class,  Engine  No. 


270  ENGINE    TESTS. 

46.  Test  No.  46  B  on  this  engine  gave  a  feed-water  consump- 
tion of  21.59  Ibs.  This  may  be  compared  with  Engine  No.  2, 
which  was  run  non-condensing  at  a  pressure  of  101  Ibs.,  and 
gave  25.8  Ibs.  consumption.  Here  the  economy  due  to  the 
compound  engine  is  4.21  Ibs.,  or  16.3%.  This  is  rather  unfav- 
orable to  the  compound  engine  on  account  of  the  relatively 
small  difference  in  the  boiler  pressures. 

Referring-  to  the  single- valve  engines  running  condensing, 
comparison  may  be  made  between  Engine  No.  41  and  Engine 
No.  19.  Engine  No.  19,  the  simple  engine,  used  27.15  Ibs.  per 
I.  H.  P.  per  hour,  and  Engine  No.  41  B,  compound,  used  19.1 
Ibs.,  the  difference  being  8.05  Ibs.,  or  an  economy  of  29.6%. 
There  are  no  single-valve  engines  of  the  non-condensing  class 
from  which  to  make  a  fair  comparison  between  the  com- 
pound and  simple  engines,  owing  to  the  great  difference  in  the 
sizes ;  but  the  results  obtained  on  engines  of  this  kind,  disre- 
garding their  size,  are  of  the  same  kind  as  those  already 
discussed. 

The  results  of  the  tests  on  the  two  triple  expansion  engines 
which  are  given,  show  an  average  consumption  of  12.63  Ibs. 
of  water  per  I.  H.  P.  per  hour.  This  is  below  the  average  of 
14.12  Ibs.  for  the  various  compound  condensing  engines  which 
are  tabulated,  and  it  is  below  the  result  obtained  from  any 
individual  engine  given  in  that  table.  It  is  better  to  the  ex- 
tent of  10%,  compared  with  the  average.  This  result  is  not, 
however,  so  good  as  that  obtained  from  the  special  com- 
pound Engine  No.  51,  where  the  ratio  of  cylinder  areas  is 
about  the  same  as  the  ratio  between  the  low-pressure  cylinder 
and  the  high-pressure  cylinder  of  triple  expansion  engines. 


VII.     ECONOMY    OF    STEAM   JACKETING    AND    RE-HEATING    IN 
COMPOUND    ENGINES. 

There  are  two  compound  engines  given  where  the  effect  of 
shutting  off  the  steam  from  the  jackets  and  re-heater  tubes 
was  tested,  these  being  No.  47  and  No.  52.  In  each  of  these 
cases,  the  difference  in  the  feed-water  consumption  per  I.  H.  P. 


REVIEW   OF  FEED-WATER    TESTS.  271 

per  hour  was  2%.  Both  of  these  are  cases  where  the  ratio 
of  area  of  the  two  cylinders  was  unusually  large,  and  the 
re-heating  surface  in  the  receiver  was  also  unusually  large, 
being  sufficient  to  superheat  the  steam  that  passed  into  the 
low-pressure  cylinder.  Whatever  value  jacketing  and  re-heating 
may  have  in  a  compound  engine,  it  may  be  reasonably  expected 
that  it  would  show  to  the  best  advantage  where  the  expansion 
is  carried  to  the  greatest  extent ;  and  consequently  the  condi- 
tions of  these  two  cases  are  as  favorable  to  a  good  showing  for 
the  jackets  as  they  could  be  in  most  engines  of  the  compound 
type.  It  would  appear  then,  that  2%  is  the  most  that  can  be 
expected  for  the  saving  of  steam  due  to  jackets  and  re-heaters 
in  ordinary  compound  engines  of  the  types  referred  to. 

There  are  none  of  the  tests  of  the  other  compound  engines 
which  furnish  much  actual  data  on  the  subject ;  but  it  may  be 
said  that  the  superficial  indications  of  the  results  of  the  tests 
where  the  engines  are  jacketed,  furnish  little  ground  for  the 
belief  that  jacketing  had  much  effect  upon  the  economy.  Take 
the  case  of  Engine  No  58  A,  which  had  no  jackets,  but  which 
was  fitted  with  a  re-heating  receiver.  The  consumption  of 
feed- water  was  13.21  Ibs.  per  I.  H.  P.  per  hour,  and  this  is 
lower  than  any  result  given  where  the  engine  was  provided 
with  jackets.  No  doubt  the  unusually  tight  condition  of  the 
valves  and  pistons  in  this  case  had  a  favorable  effect;  but  if 
jacketing  is  necessary  for  good  economical  results  and  the 
advantage  it  produces  is  a  marked  one,  its  absence  in  Engine 
No.  58  should  have  produced  a  much  ^more  noticeable  effect. 

Beyond  the  saving  in  steam  consumption  produced  by  jack- 
ets, which  in  Engines  No.  47  and  53  amounted  to  2%,  there 
is  a  further  saving  in  fuel  which  cannot  be  overlooked,  which 
may  be  obtained  by  returning  the  hot  water  condensed  in  the 
jackets  to  the  boilers.  The  temperature  of  this  water  is 
ordinarily  about  300°,  and  its  quantity  on  the  tests  noted 
was  7.7%  in  one  case,  and  11%  in  the  other,  averaging 
9.3%  for  the  two.  If  the  temperature  of  the  main  supply 
of  feed- water  is  100°,  the  return  of  this  water  to  the  boilers 
would  add  about  19°  to  the  temperature  of  the  feed-water, 


272  ENGINE    TESTS. 

and  increase  the  efficiency  of  the  boilers  a  little  less  than 
2%.  If  the  temperature  of  the  main  feed-water  was  at  a 
higher  point,  the  effect  of  the  heat  returned  from  the  jackets 
would  be  correspondingly  less.  If  we  make  this  for  an  aver- 
age case,  l-J-%?  we  should  have  the  combined  economy  of  the 
jackets  due  to  both  causes  about  3£%. 

There  is  one  test  of  a  compound  engine  which  was  made  to 
determine  the  effect  of  shutting  off  the  steam  from  the  re- 
heater,  in  a  case  where  the  cylinders  were  unjacketed.  This  re- 
lates to  Engine  No.  48.  Test  A  was  made  with  the  re-heater 
on,  and  test  B  with  the  re-heater  off.  The  figures  show  that 
the  engine  was  the  most  economical  in  the  latter  case,  the 
difference  between  .11  of  a  pound  or  .7  of  1%  ;  so  that  in 
this  one  instance  it  would  seem  that  the  use  of  the  re- 
heater  produced  a  loss  in  steam  consumption  instead  of  a 
gain.  If  allowance  is  made  for  the  heat  which  could  be  re- 
turned from  the  water  of  condensation  to  the  boilers,  the 
advantage  from  this  source  would  be  nearly  1%,  so  that 
there  was  a  slight  advantage  in  fuel  economy  due  to  the  use 
of  the  re-heater. 

Whatever  the  actual  economy  due  to  jacketing  or  to  re- 
heating or  to  both,  which  from  the  evidence  of  these  tests 
appears  to  be  rather  small,  there  is  no  question  but  that  the 
action  of  the  jacket  and  the  re-heater  produces  a  powerful  in- 
fluence on  the  steam  in  its  passage  through  the  cylinders.  The 
effect  upon  the  indicator  diagrams  is  very  marked.  The  use 
of  these  appliances  makes  the  engine  more  powerful  in  view  of 
the  fact  that  it  increases  the  work  done  by  the  low-pressure 
cylinder  for  a  given  amount  performed  by  the  high-pressure 
cylinder.  In  Engine  No.  47,  the  low-pressure  cylinder  de- 
veloped 34  horse-power  less  than  the  high-pressure  cylinder 
when  the  jackets  and  re-heater  were  off,  and  10  horse-power 
more  than  the  H.  P.  cylinder  when  the  jackets  were  on.  In 
Engine  No.  52,  the  low-pressure  cylinder  developed  24  horse- 
power more  than  the  H.  P.  cylinder  when  the  jackets  and  re- 
heater  were  off,  and  92  horse- power  more  when  the  jackets 
were  on.  In  Engine  No.  48,  the  low-pressure  cylinder  de- 


REVIEW   OF  FEED-WATER    TESTS.  273 

veloped  56  horse-power  less  than  the  H.  P.  cylinder  when  the 
re-heater  was  off,  and  19  horse-power  less  when  the  re-heater 
was  on. 

The  effect  of  the  jacketing  and  re-heating  is  also  seen  to 
be  very  marked  when  comparison  is  made  between  the  steam 
accounted  for  in  the  two  cylinders.  In  Engine  No.  47,  with 
the  jackets  off,  the  steam  accounted  for  in  the  L.  P.  cylinder 
at  cut-off  is  10.8%  less  than  in  the  H.  P.  cylinder;  whereas 
with  the  jackets  on,  the  difference  is  only  1%.  In  Engine 
No.  52,  with  jackets  off,  the  steam  accounted  for  in  the  L.  P. 
cylinder  is  8.4%  less  than  in  the  H.  P.  cylinder.  When 
the  jackets  were  on,  it  was  12.9%  more  than  in  the  H.  P. 
cylinder.  In  Engine  No.  48,  the  steam  accounted  for  in 
the  L.  P.  cylinder  with  the  re-heater  off,  was  11.6%  less 
than  that  in  the  H.  P.  cylinder ;  whereas,  when  the  re-heater 
was  on,  it  was  only  4.2%  less.  In  Engine  No.  55  the  effect 
of  the  re-heater  on  the  diagrams  is  seen  to  be  considerable, 
from  the  fact  that  the  steam  accounted  for  in  the  L.  P. 
cylinder  is  1.3%  more  than  that  accounted  for  in  the  H.  P. 
cylinder. 

VIII.       EFFECT    OF    RATIO    OF    CYLINDER    AREAS    IN 
COMPOUND    ENGINES. 

In  most  of  the  compound  engines  given,  where  these  are  of 
the  Corliss  or  other  4-valve  type,  the  ratio  of  cylinder  areas  is 
between  3.5  and  4.  Three  cases  are  given,  however,  where 
the  ratio  is  about  7  to  1,  these  being  Engines  47,  51,  and  52. 
The  engines  with  the  large  ratio  of  cylinder  area  show  more 
economical  results  than  the  others.  The  difference  is  not  so 
noticeable  in  No.  52  as  it  is  in  Nos.  47  and  51.  In  both  these 
cases,  however,  the  pressure  is  higher  than  it  is  in  most  of  the 
tests  given  with  the  lower  ratios ;  and  this  higher  pressure  fur- 
nishes one  reason  for  the  better  result.  There  is  one  case  of  a 
pressure  of  151  Ibs.  in  an  engine  having  a  low  ratio  with  which 
these  may  be  compared,  and  that  is  Engine  No.  55.  This 
engine  gives  a  horse-power  for  13.27  Ibs.  of  feed-water  per 


274  ENGINE    TESTS. 

hour.  Engine  No.  47  B  gives  12.45  Ibs.,  while  Engine  No. 
51  C,  gives  11.89  Ibs.  Taking  the  average  of  the  last  two, 
which  is  12.17,  there  is  a  difference  between  the  two  cases  in 
favor  of  the  larger  ratio  of  areas  of  1.1  Ibs.  or  8%.  Engine 
No.  55,  as  will  be  seen,  does  not  give  so  well-formed  diagrams, 
there  being  considerable  wiredrawing  in  the  H.  P.  cylinder; 
and  the  result  obtained  on  this  engine  is  not  so  good  as  it 
would  have  been  if  these  conditions  had  been  better.  Making 
due  allowance  for  this,  however,  and  further  allowance  for  the 
fact  that  Engine  No.  51  was  supplied  with  slightly  superheated 
steam,  there  appears  to  be  a  noticeable  advantage  in  the  use  of 
the  higher  ratio  of  cylinder  area  for  an  engine  running  at  150 
Ibs.  pressure.  It  is  a  noteworthy  fact  that  with  the  high  ratio 
of  area,  an  excellent  steam  distribution,  and  a  slight  amount  of 
superheating,  the  most  economical  result  given  in  the  whole  list 
of  tests  is  produced,  —  Engine  No.  51  C  producing  a  horse- 
power for  11.89  Ibs.  of  feed- water  per  hour. 

IX.     MISCELLANEOUS. 

The  tests  furnish  some  indication  as  to  the  loss  of  economy 
produced  by  light  loads,  especially  in  non-condensing  engines. 
In  Engine  No.  16,  which  is  a  single-valve,  single-acting  engine 
of  the  high-speed  class,  the  consumption  of  steam  per  horse- 
power per  hour  was  increased  from  32.6  Ibs.  to  36.27  Ibs.,  by 
reducing  the  horse-power  developed  from  44.8  H.  P.  to  25.7 
H.  P.  In  Engine  No.  23,  which  is  of  the  single-valve  high- 
speed class,  the  consumption  increased  from  30.63  Ibs.  to  31.78 
Ibs.,  corresponding  to  a  reduction  of  load  from  39.4  H.  P.  to 
22.2  H.  P.  In  Engine  No.  31,  which  is  of  the  Corliss  type,  the 
consumption  was  fairly  constant  with  a  load  varying  from  222 
H.  P.  to  342  H.  P.,  but  with  lighter  loads  it  rapidly  fell  off; 
and  with  the  load  of  the  idle  engine  and  shafting,  which  was  37 
horse-power,  the  consumption  rose  to  73.63  Ibs.  per  I.  H.  P.  per 
hour.  In  Engine  No.  42,  which  is  a  single-valve  high-speed 
compound,  the  consumption  was  increased  from  25.2  Ibs.  to 
44.89  Ibs.  by  reducing  the  load  from  152.5  H.  P.  to  45.6  H.  P. 


REVIEW   OF  FEED-WATER    TESTS.  275 

In  Engine  No.  54,  which  is  a  single-valve  compound,  the  feed- 
water  consumption,  was  nearly  constant  for  loads  of  242.9  H.  P. 
and  187.5  H.  P. ;  but  it  was  increased  from  21.14  Ibs.  to  24.99 
Ibs.  by  dropping  the  load  to  103.4  H.  P.  In  Engine  No.  41,  a 
single-valve  compound  condensing,  the  consumption  was  in- 
creased from  19.1  Ibs.  to  22.74  Ibs.  by  reducing  the  load  from 
196.8  H.P.  to  90.5  H.P.  In  Engine  No.  45,  which  is  a  double- 
valve  compound  condensing,  the  consumption  was  increased 
from  15.71  Ibs.  to  17.22  Ibs.  by  reducing  the  load  from  244.5 
H.  P.  to  123.4  H.  P. 

Very  little  information  of  definite  character  is  furnished  by 
the  tests  as  to  the  effect  of  size  of  cylinder  on  economy.  Most 
of  the  smaller  engines  given  are  of  the  single-valve  class,  with 
shaft  governors,  running  at  high  speed;  and  although  these 
generally  show  less  economy  than  the  larger  engines,  it  would 
hardly  be  fair  to  attribute  it  to  the  smaller  size  of  cylinder 
when  other  differences  of  condition  are  known  to  be  of  much 
importance.  Two  cases  are  given  for  Corliss  engines  which 
seem  to  show  that  a  considerable  difference  of  size  has  no 
appreciable  effect.  These  are  Engine  No.  2,  having  a  28.5 " 
x  59.5"  non-condensing  cylinder,  and  Engine  No.  31,  which 
had  2-1 6 "  x  42"  cylinders.  The  former  gave  a  horse-power  for 
25.8  Ibs.  of  feed-water  per  hour ;  and  the  latter,  when  working 
at  about  the  same  cut-off,  for  25.9  Ibs.  per  hour,  or  practically 
the  same  result.  Cylinder  condensation  and  leakage  is  2.1% 
greater  in  the  case  of  the  smaller  engine ;  and  this  fact  fur- 
nishes a  slight  indication  that  the  smaller  engine  was  the  more 
wasteful. 

It  needs  but  a  glance  at  the  results  of  the  various  tests  to 
show  that  the  4-valve  engines  are  more  economical  as  a  type 
than  those  having  a  less  number  of  valves ;  and  this  is  true 
whether  they  are  simple  or  compound,  and  whether  condensing 
or  non-condensing.  The  single-valve  compound  non-conden- 
sing Engine  No.  54,  compared  with  the  4-valve  compound 
non-condensing  Engine  No.  46,  shows  a  better  result,  some 
2% ;  but  it  will  be  observed  that  the  former  works  under  a 
pressure  of  165  Ibs.,  while  the  pressure  in  the  latter  case  is  135. 


276  ENGINE    TESTS. 

As  the  economy  of  non-condensing  compound  engines  is  greatly 
affected  by  the  boiler  pressure,  the  single-valve  engine  in  this 
case  has  an  undoubted  advantage,  which  more  than  makes  up 
for  the  difference  produced  hy  the  valve.  The  superior  econ- 
omy of  the  4-valve  type  is  evidently  due  in  part  to  the  better 
distribution  of  the  steam  in  the  cylinders,  as  revealed  by  more 
perfectly  formed  diagrams ;  and,  in  some  cases  to  the  tighter 
condition  of  the  valves  and  pistons. 

One  test  is  given  that  shows  the  loss  in  economy  due  to  the 
variable  load  produced  in  electric  railway  service.  This  is 
Engine  No.  58  B,  which  is  a  Corliss  compound  condensing 
engine.  Compared  with  test  No.  58  A,  which  was  made 
with  the  same  engine  working  under  a  steady  load,  the  loss  is 
only  2.5%.  On  the  test  with  the  variable  load,  the  average 
power  was  843.4  H.  P.,  while  that  with  the  steady  load  was 
1030.1  H.  P.  It  is  evident  that  the  difference  in  economy 
shown  was  caused  to  a  considerable  extent,  if  not  wholly,  by 
the  fact  that  in  the  variable  load  the  engine  is  at  times  under- 
loaded, and  not  working  to  its  best  economical  advantage. 
This  was  probably  an  unusually  favorable  showing  for  a  varia- 
ble load  in  the  service  mentioned,  for  the  reason  that  the  range 
of  variation  was  less  than  occurs  in  much  work  of  this  kind. 
An  examination  of  the  indicator  diagrams  gives  some  idea  of 
the  extent  of  the  variation. 

One  method  of  reducing  the  loss  of  steam  where  compound 
engines  are  used,  is  to  exhaust  the  air-pump  into  the  receiver 
of  the  engine.  This  virtually  converts  the  air-pump  from  a 
simple  engine  to  a  compound  engine.  The  effect  of  thus  util- 
izing the  exhaust  steam  of  the  air-pump  is  seen  in  test  No.  57. 
The  effect  is  shown  by  the  large  increase  of  the  amount  of 
steam  accounted  for  in  the  low-pressure  cylinder,  as  compared 
with  that  in  the  high-pressure  cylinder.  The  increase  is  from 
.696  to  .80,  or  .104.  In  Engine  No  55,  which  is  of  similar 
type  except  in  this  particular,  the  increase  is  only  .013  ;  and  in 
Engine  No.  58  A,  also  similar  in  type,  there  is  a  falling  off  of 
.08.  In  Engine  No.  57,  the  steam  used  by  the  air-pump  when 
exhausting  into  the  condenser  amounted  to  .9  of  a  pound  per. 


REVIEW   OF  FEED- WATER    TESTS.  277 

I.  H.  P.  per  hour,  and  when  exhausting  into  the  receiver  it 
was,  of  course,  a  much  larger  quantity;  but  in  spite  of  this 
the  extra  power  produced  by  the  use  of  the  steam  in  the  low- 
pressure  cylinder  was  such  that  the  entire  consumption  of 
the  engine  and  condenser  was  only  14.1  Ibs.  per  I.  H.  P.  per 
hour. 

One  test  on  a  compound  engine  is  given,  where  the  water 
drained  from  jackets  and  receiver  was  pumped  into  a  flue 
heater,  and  the  steam  produced  by  its  re-evaporation  brought 
back  to  the  receiver  and  used  in  the  low-pressure  cylinder. 
This  is  Engine  No.  50.  Under  the  circumstances  of  a  compar- 
atively low  boiler  pressure,  which  was  108.1  Ibs.,  the  economi- 
cal result  obtained,  which  was  13.28  Ibs.  per  I.  H.  P.  per  hour, 
must  be  considered  excellent.  The  engine,  however,  was  sup- 
plied with  superheated  steam ;  and  this  condition  is,  no  doubt, 
accountable,  in  some  degree  at  least,  for  the  result  obtained. 
It  is  doubtful  whether  the  re-heating  had  any  marked  effect ; 
because  it  appears  that  the  steam  accounted  for  in  the  L.  P. 
cylinder  is  .77  as  against  .889  in  the  H.  P.  cylinder,  showing  a 
loss  between  the  two  of  .119.  If  this  is  compared  with  Engine 
No.  49,  which  is  supplied  with  ordinary  steam,  and  had  no 
re-heating  feature,  there  is  a  difference  between  the  two  cylin- 
ders of  .106 ;  so  that  there  is  no  more  loss  in  this  case  between 
the  cylinders  than  in  Engine  No.  50,  which  had  the  re-heating 
system. 

The  evidence  of  the  tests  furnish  some  data  upon  the  effect 
of  varying  the  receiver  pressure  in  a  compound  engine,  but 
this  data  is  not  conclusive  as  applied  to  other  engines.  In  the 
case  of  Engine  No.  51,  three  tests  made  with  nearly  the  same 
load  and  with  a  receiver  pressure,  ranging  from  5.4  Ibs.  above 
the  atmosphere  to  12.9  Ibs.,  the  cut-off  in  the  low-pressure 
cylinder  being  gradually  shortened  as  the  pressure  increased, 
showed  a  gradual  reduction  in  the  feed-water  consumed  per 
I.  H.  P.  per  hour.  With  the  lowest  pressure,  it  was  12.29  Ibs., 
and  with  the  highest,  11.89  Ibs.  In  Engines  No.  47  and  52, 
where  similar  tests  were  made  with  three  different  receiver 
pressures,  practically  the  same  result  is  produced  at  the  two 


278  ENGINE    TESTS. 

extreme  pressures.  In  one  case,  the  intermediate  pressure  gave 
a  slight  reduction,  whereas  in  the  other,  the  intermediate  pres- 
sure gave  a  slight  increase  in  the  consumption. 

IN    CONCLUSION. 

A  careful  study  of  these  tests  should  be  of  service  to  engi- 
neers in  designing  new  plants  or  re-organizing  old  ones,  inas- 
much as  they  show,  within  the  limits  covered,  what  designs 
and  practices  should  be  avoided,  and  what  conditions  should  be 
observed  in  order  to  secure  desired  results  in  the  best  manner. 


VALVE   SETTING. 


279 


ENGINE   No.   61. 

Double  valve,  6"  x  14".     Speed,  210  revolutions  per  minute. 

This  is  an  automatic  cut-off  engine  with  slide  valves  and 
shaft  governor.  The  main  valve  is  of  the  box  pattern,  with 
balance  plates  on  the  back  face.  Steam  is  admitted  into  the 
interior  of  the  box  before  it  passes  through  the  ports  into  the 
cylinder.  The  cut-off  valve  rides  on  a  seat  inside,  and  is 
operated  by  a  separate  eccentric,  which  is  shifted  by  the  action 
of  a  shaft  governor.  The  diagrams  here  given  show  the  effect 
of  moving  the  eccentric  which  operates  the  main  valve  an 
angular  distance  of  43°  on  the  shaft.  This  represents  a  dis- 
tance of  14-"  on  a  shaft  4"  in  diameter.  No.  61a  was  taken 
before,  and  No.  615  after,  the  change. 


ENGINENo.  61a 


ENGINE  No.  61b 


281 


ENGINE   No.   62. 

Four  valve,  16"x48".     Speed,  82  revolutions  per  minute. 

This  engine  is  of  the  4-valve  type,  the  steam  valves  being 
slide  valves,  and  the  exhaust,  Corliss  valves.  They  are  oper- 
ated by  separate  eccentrics.  Changes  in  the  setting  of  the 
valves  consisted  in  moving  the  steam-valve  eccentric  ahead 
2"  measured  on  the  circumference  of  the  8"  shaft,  moving  the 
exhaust  eccentric  ahead  $",  adjusting  the  tappet  which  operates 
the  steam  valve  so  as  to  obtain  earlier  admission,  and  shorten- 
ing the  exhaust-valve  rod  two  turns  to  obtain  earlier  release. 
The  diagrams  were  taken  from  the  head  end,  No.  62  a  before, 
and  No.  626  after,  the  change. 

In  connection  with  these  changes  feed-water  tests  were  made 
which  showed  a  saving  of  8  %  on  the  steam  used  by  the  plant 
of  which  this  engine  formed  a  part;  the  total  power  of  the 
plant  being  somewhat  more  than  twice  the  power  developed 
by  this  engine. 


ENGINE  No.  62a 


282 


ENGINE   No.   63. 

Four  valve  (Corliss),  18"  x  48".  Speed,  57  revolutions  per 
minute. 

This  engine  is  of  the  ordinary  Corliss  type  with  single  eccen- 
tric. The  changes  in  the  valves  consisted  in  moving  the 
eccentric  forward  -J-  inch  on  a  10"  shaft,  and  shortening  the 
steam-valve  rod  4  turns,  or  4  threads.  The  diagrams  were 
taken  from  the  head  end,  No.  63#  before,  and  No.  636  after, 
the  change. 


ENGINE  No.63a' 


ENGINE  No.63b 


283 


ENGINE   No.   64. 

Four  valve  (Corliss),  23"  x  48".  Speed,  51  revolutions  per 
minute. 

The  steam-valve  rod  was  lengthened  6  turns,  or  6  threads, 
to  reduce  the  lead.  The  diagrams  are  from  the  crank  end, 
No.  64a  being  taken  before,  and  No.  646  after,  the  adjustment. 


ENGINE  No.  64a 


ENGINE  No.  64b 


284 


ENGINE    No.   65. 


Speed,  67  revolutions  per 


Four  valve  (Corliss),  14"  x  36". 
minute. 

The  eccentiic  was  moved  forward  f "  on  the  7"  shaft.  The 
steam-valve  rod  was  shortened  6  turns  or  6  threads.  The  dia- 
grams are  from  the  head  end,  No.  65a  being  taken  before,  and 
No.  656  after,  the  change. 


ENGINE  No.  65a 


285 


ENGINE   No.    66. 

Four  valve  (Corliss),  26"  x  60".  Speed,  51  revolutions  per 
minute. 

The  changes  in  the  valve-setting  consisted  in  moving  the 
eccentric  forward-^"  on  the  12"  shaft  and  shortening  the  ex- 
haust-valve rod  2y  turns,  or  5  threads,  so  as  to  secure  earlier 
release.  The  diagrams  are  from  the  head  end  of  the  cylinder, 
No.  66a  being  taken  before,  and  No.  665  after,  the  change. 


ENGINE  No.  66a 


286 


ENGINE    No.   67. 

Single  valve,  8"  x  10".     Speed,  326  revolutions  per  minute. 

This  engine  is  of  the  automatic  cut-off  type  with  shaft  gov- 
ernor, shifting  eccentric,  and  balanced  slide  valve.  These 
diagrams  show  the  effect  of  unequal  adjustment  of  the  lap  of 
the  valve.  The  first  set,  67 a  and  676,  was  taken  with  the 
engine  loaded.  The  mean  effective  pressure  at  the  head  end 
is  8  Ibs.,  and  at  the  crank  end,  32.4  Ibs.  The  second  set,  61  c 
and  67c?,  was  taken  with  a  friction  load.  Here  the  mean  effec- 
tive pressure  at  the  head  end  is  a  minus  quantity,  and  at  the 
crank  end  a  plus  quantity.  The  third  set,  670  and  67/,  was 
taken  under  the  same  conditions  of  load  as  the  second,  after 
equalizing  the  lap.  With  this  adjustment  the  mean  effective 
pressure  at  the  head  end  was  1.9  Ibs.,  and  at  the  crank  end, 
3.4  Ibs. 


ENGINE  No.67a 


Head  End 


-30 

20 

—  10 

0 


ENGINE  No.  67b 


Crank  End 


-60 
-50 
-40 
-30 
-20 
-10 
-  0 


287 


ENGINE  No.  67c 


Head  End 


30 

20 

10 

-  O 


ENGINE  No.  67d 


Crank  End 


70 

60 

50 

40 

30 

20 

-10 

0 


ENGINE  No.  67e 


Head  End 


30 

20 

10 

0 


ENGINE  No.  67f 


Crank  End 


-40 
30 
-20 
-10 
-  0 


ENGINE    No.    68. 

Four  valve,  13"  x  36".     Speed,  61  revolutions  per  minute. 

This  engine  has  double  poppet  valves  for  admission,  and 
slide  valves  for  exhaust.  The  valves  are  operated  by  a  train 
of  gears  and  cams.  The  adjustments  consisted  in  moving  for- 
ward the  cam  which  operates  the  steam  valve  so  as  to  produce 
earlier  admission.  The  diagrams  are  taken  from  the  head  end, 
No.  68#  before,  and  685  after,  the  changes. 


ENGINE  No.  68a 


ENGINE  No.  68b 


289 


ENGINE   No.   69. 

Four  valve,  11"  x  30".     Speed,  80  revolutions  per  minute. 

This  engine  has  double-poppet  admission  valves,  and  slide 
valves  for  exhaust ;  all  driven  by  a  train  of  gears. 

The  steam- valve  cam  was  moved  forward  1"  on  its  shaft,  and 
the  exhaust  cam  £".  The  diagrams  are  taken  from  the  crank 
end,  No.  69a  before,  and  No.  696  after,  the  adjustments. 


ENGINE  No.  69a 


J 


290 


ENGINE   No.   70. 

Four  valve,  18"  x  42".     Speed,  55  revolutions  per  minute. 

In  this  engine  the  steam  valves  are  double  poppet,  and  the 
exhaust  valves,  slides.  The  mechanism  is  driven  by  means  of 
bevel  gears.  The  adjustment  of  the  valves  consisted  in  moving 
the  driving-gear  forward  on  the  shaft  two  teeth.  The  total 
number  of  teeth  on  this  gear  was  44.  The  diagrams  are  from 
the  head  end,  No.  70a  being  taken  before,  and  No.  706  after, 
the  changes. 


ENGINE  No.  70a 


ENGINE  No.  7Ob 


291 


ENGINE    No.    71. 

Four  valve,  14"  x  35".     Speed,  49  revolutions  per  minute. 

This  engine  has  two  double-poppet  steam  valves,  and  slide 
valves  for  the  exhaust;  all  driven  through  a  train  of  gears. 
The  changes  consisted  in  moving  the  stem  of  the  steam  valve 
in  so  as  to  clear  the  driving-cam,  and  setting  the  gear  forward 
on  the  shaft  2  teeth.  The  diagrams  were  taken  from  the  head 
end,  No.  71#  before,  and  No.  716  after,  the  adjustments. 


ENGINENo.  71a 


ENGINE  No.  71b 


292 


ENGINE    No.   72. 

Four  valve,  16"  x  36".     Speed,  72  revolutions  per  minute. 

This  engine  has  two  double-poppet  steam  valves,  and  slide 
valves  for  the  exhaust.  They  are  driven  through  a  train  of 
gears. 

The  gear  which  drives  the  valves  was  changed,  with  a  view 
to  securing  compression  of  the  exhaust  steam  up  to  the  initial 
pressure,  being  moved  forward,  thereby  hastening  the  release 
as  well  as  the  compression.  This  change  was  made  with  the 
object  of  studying  the  effect  of  compression  upon  the  actual 
economy  of  the  engine  under  conditions  of  practically  the  same 
oad.  So  far  as  this  test  showed  anything,  under  these  condi- 
tions, there  was  in  reality  a  slight  increase  in  the  amount  of 
feed-water  consumed  per  horse-power  per  hour,  attending  the 
earlier  compression.  The  diagrams  were  taken  from  the  crank 
end,  No.  72a  before,  and  No.  726  after,  the  change. 

ENGINE  No.  72a 


ENGINE  No.  72b 


293 


ENGINE    No.    73. 

Four  valve,  26"  x48".     Speed,  50  revolutions  per  minute. 

The  steam  valves  in  this  engine  are  slide  valves,  and  the 
exhaust  are  Corliss  valves. 

The  change  here  consisted  in  moving  the  driving-gear  for 
the  steam  valves  one  tooth  ahead,  the  total  number  being  42, 
and  in  shortening  the  exhaust  rod  so  as  to  reduce  the  lap  on 
the  exhaust  valve.  The  diagrams  were  taken  from  the  head 
end,  No.  73a  before,  and  No.  736  after,  the  changes. 


ENGINE  No.  73a 


ENGINE  No.  73b 


294 


ENGINE   No.   74. 

Four  valve,  18"  x48".     Speed,  64  revolutions  per  minute. 

All  the  valves  in  this  engine  are  slides  driven  by  double  ec- 
centrics. The  adjustments  consisted  in  advancing  the  steam- 
valve  eccentric  1J-"  on  the  9"  shaft,  and  the  exhaust  eccentric 
%  inch.  The  diagrams  were  taken  from  the  head  end,  No. 
74a  before,  and  No.  746  after,  the  changes. 


ENGINE  No.  74a 


ENGINE  No.  74b 


295 


ENGINE    No.    75. 

Four  valve  (Corliss),  30"  x  48."  Speed,  80  revolutions  per 
minute.  The  setting  of  the  valves  was  changed  by  the  intro- 
duction of  a  separate  eccentric  for  driving  the  exhaust  valves, 
and  the  adjustment  of  this  eccentric  so  as  to  obtain  early 
compression.  With  a  single  eccentric  the  engine  operated 
unsatisfactorily  on  account  of  the  noisy  action  of  the  piston 
and  valves,  there  being  decided  and  annoying  sounds  at  each 
end  of  the  stroke,  which  could  be  distinctly  heard  by  a 
person  standing  at  a  distance  of  20  feet  from  the  cylinder. 
When  the  additional  eccentric  had  been  applied  and  the  valves 
readjusted,  the  troublesome  sounds  so  far  disappeared  that  it 
was  necessary  for  the  observer  to  hold  his  ear  close  to  the 
cylinder  to  be  aware  of  any  disturbance.  The  diagrams  were 
taken  from  the  head  end,  and  for  ready  comparison,  they  are 
superimposed,  the  full  line  being  taken  with  single  eccentric 
and  the  dotted  line  after  changing  to  double  eccentrics  and  re- 
setting the  valves. 


ENGINE  No.  75 


296 


ENGINE    No.  76. 

Four  valve,  20"  x  50."     Speed,  64  revolutions  per  minute. 

This  engine  has  four  slide  valves,  all  operated  by  means  of 
a  train  of  gears.  The  diagram  here  given  is  presented  as  a 
curiosity,  showing  the  effect  of  admission  of  steam  to  the 
cylinder  subsequent  to  the  cut-off,  due  to  the  rebounding  of 
the  valve  after  it  had  once  closed.  The  diagram  was  taken 
from  the  crank  end  of  the  cylinder. 


ENGINE  No.  76 


297 


ENGINE    No.    77. 

Elevator  Engine,  8"  x  10." 

This  is  introduced  as  a  curiosity,  and  at  the  same  time  it 
reveals  the  wasteful  character  of  this  class  of  engine.  There 
is  an  absence  of  expansion  and  exceedingly  high  back  pressure, 
both  of  which  are  required  by  the  exigencies  of  the  service  and 
type  of  valve  mechanism  which  that  service  necessitates.  This 
diagram  also  illustrates  the  effect  of  improper  location  of  the 
indicator  on  the  cylinder.  In  this  case  it  was  placed  at  a  short 
distance  from  the  end.  of  the  stroke,  so  that  the  piston  ring 
covered  the  hole  until  it  had  moved  a  certain  distance  on  the 
forward  stroke.  The  hump  on  the  diagram  is  caused  by  this 
defective  location. 

The  diagram  was  taken  on  an  upward  trip. 


ENGINE  No.77 


298 


ENGINE    No.    78. 


Four  valve  (Corliss),  23"  x  60."     Speed,  74  rev.  per  min. 

These  diagrams  furnish  another  instance  showing  the  in- 
fluence, or  want  of  influence,  of  leakage.  In  this  case  the 
trouble  was  with  the  piston.  Diagram  No.  78a  was  taken  with 
the  piston  leaking,  the  packing  ring  being  broken,  and  No.  786 
was  taken  when  the  ring  had  been  renewed,  and  the  piston 
made  tight.  Feed-water  tests  made  under  both  conditions 
showed  that  the  leaking  engine  used  34.5  Ibs.  of  steam  per  I.  H. 
P.  per  hour,  and  the  tight  engine,  27.7  Ibs.  The  difference  is 
about  20  °/0.  The  boiler  pressure  was  higher  after  the  repairs 
than  before,  but  this  does  not  affect  the  general  features.  So 
far  as  the  expansion  line  is  concerned,  the  leakage  of  the  piston 
had  no  appreciable  effect.  There  is  a  noticeable  difference  in 
the  compression  lines,  but  in  the  leaking  engine  this  alone 
would  not  prove  the  leakage  in  question.  The  diagrams  are 
from  the  crank  end. 


ENGINE  No.  78a 


ENGINE  No.  78b 


-60 


-40 


-20 


0 
1-80 


-60 


-40 


-20 


L    0 


299 


ENGINE    No.  79. 

Four  valve  (Corliss),  cross  compound,  24"  and  44"  x  72." 
Speed,  61  revolutions  per  minute. 

The  main  object  in  changing  the  adjustment  of  the  valves  in 
this  engine  was  to  secure  a  greater  amount  of  compression,  and 
a  more  quiet  operation  of  the  engine.  Previous  to  the  changes 
there  was  considerable  knocking  in  the  main  connections  when 
the  centers  were  passed,  and  internal  noises  in  both  cylinders. 
The  effect  of  the  changes  was  to  almost  wholly  overcome  these 
defects  in  the  running  qualities.  The  adjustments  consisted 
in  moving  the  eccentric  of  the  high-pressure  cylinder  forward 
jj"  on  the  12"  shaft  and  the  eccentric  of  the  low-pressure 
cylinder  forward  l£."  The  steam-valve  rods  of  the  high-pres- 
sure cylinder  were  both  shortened  two  threads,  so  as  to  give 
earlier  admission.  The  exhaust  rods  of  the  same  cylinder  were 
lengthened  8  threads  each,  so  as  to  increase  the  compression. 
The  steam-valve  rods  of  the  L.  P.  cylinder  were  shortened  three 
threads  each,  so  as  to  give  earlier  admission ;  and  the  exhaust 
rods  were  each  lengthened  6  threads,  so  as  to  obtain  earlier  com- 
pression. To  better  reveal  the  effect  of  the  changes,  the  dia- 
grams are  superimposed,  the  dotted  lines  being  taken  before, 
and  the  full  lines  after,  the  adjustments. 


300 


ENGINE  No.  79 


lOO- 
SC - 
60- 
40 
20- 
0- 


H.P.  Head  End 


H.P.  Crank  End 


-!00 

-  80 

-  60 
-40 

-  20 

-  O 


L.P.  Head  End 


L.P.  Crank  End 


ENGINE   No.    80. 

Four  valve  (Corliss)  tandem  compound,  18"  and  30"  x  48". 
Speed,  63  revolutions  per  minute. 

The  low-pressure  cylinder  of  this  engine  was  operated  by 
double  eccentrics.  The  diagrams  here  given  show  the  effect 
produced  by  advancing  the  eccentric  which  drives  the  exhaust 
valves  of  the  low-pressure  cylinder  3-J-"on  the  12"  shaft.  At 
the  same  time  the  exhaust  rod  on  the  high-pressure  cylinder  was 
lengthened  2  threads,  so  as  to  give  greater  compression.  The 
diagrams  were  taken  at  the  head  end  of  both  cylinders,  No. 
80a  before,  and  No.  SOb  after,  the  adjustments. 


302 


120- 

100- 

80- 

60- 

40- 

20- 

0- 


ENGINENo.  8Oa 


H.P.  Cyl, 


UP.  Cyl. 


-  15 

-  10 

-  5 

-  0 

O 

-  10 


ENGINE  No.  8Ob 


I20-, 

100 
80J 
60 
40- 
20- 

o- 


H.P.  Cyl. 


L.P.  Cyl. 


-  15 

-  10 
—    5 

-    0 

-  5 

-  10 


ENGINE    No.  81. 

Compound  duplex  direct  acting  pumping  engine. 

These  diagrams  show  the  effect  of  increasing  the  throw  of 
the  valves  (which  are  slide  valves),  thereby  giving  the  engine 
the  benefit  of  wider  opening  of  ports.  The  improvement  is 
shown  mainly  in  the  increased  effect  of  the  vacuum  in  the  low- 
pressure  cylinder.  The  effect  of  the  change  on  the  duty  per- 
formed by  the  pump  was  marked,  and  the  consumption  of  coal 
was  much  reduced.  No.  8~La  was  taken  before,  and  No.  81  b 
after,  the  change. 


ENGINE  No.  Sla 


60 


-   40 


304 


ENGINE    No.  82. 

Four  valve  cross  compound,  24"  and  46"  x  48".  Speed, 
75  revolutions  per  minute. 

The  high-pressure  cylinder  of  this  engine  is  of  the  four-valve 
type.  The  low-pressure  cylinder  has  slide  valves  with  cut-off 
adjustable  by  hand.  These  diagrams  show  the  effect  upon  the 
distribution  of  the  load  between  the  cylinders  produced  by 
changing  the  cut-off  in  the  low-pressure  cylinder.  In  one  case, 
No.  82 a,  it  was  set  at  the  J  mark,  and  the  other,  No.  826,  at  the 
|  mark.  In  the  former  the  power  developed  by  the  high-pressure 
cylinder  was  408  H.  P.,  and  by  the  low-pressure  cylinder  300 
H.  P.,  while  in  the  latter  the  quantities  were  respectively 
480  and  222.  The  diagrams  are  from  the  crank  end. 


305 


OF   THK 

UNIVERSITY 


ENGINE  No.  82a 


H.P.  Cyl. 


100 
-80 
•60 
-40 
-20 
-  0 


L.P.  Cyl. 


-  10 

-  5 
-  0 

—  5 

L-  10 


ENGINE  No.  82b 


H.P.  Cyl. 


r-100 

80 
_  60 

-40 
-20 
-  0 


L.P.  Cyl. 


ENGINE    No.  83. 

Canadian  cross-compound  engine,  20"  and  36"  x  42".  Speed, 
76  revolutions  per  minute. 

The  high-pressure  cylinder  in  this  engine  has  Corliss  valves 
and  the  usual  automatic  cut-off.  The  low-pressure  cylinder  has 
a  plain  slide  valve  with  no  means  of  adjusting  the  cut-off  save 
by  shifting  the  eccentric.  These  diagrams  show  the  effect 
upon  the  distribution  of  the  load  between  the  cylinders  pro- 
duced by  changing  the  low-pressure  cut-off  by  the  eccentric 
adjustment.  When  the  steam  followed  in  the  low-pressure 
cylinder  to  nearly  full  stroke  No.  83  a,  the  power  developed  in 
the  high-pressure  cylinder  was  167  H.  P.,  and  in  the  low-pres- 
sure cylinder,  60  H.  P.  When  the  eccentric  was  advanced  in 
the  low-pressure  cylinder,  No.  83  &,  these  quantities  became 
respectively  149  H.  P.  and  80  H.  P. 


307 


ENGINE  No.  83a 


H.P.  Cyl. 


—  60 


-40 


-20 


-    0 


L.P.  Cyl. 


ENGINE  No.  83b 


H.P.  Cyl. 


^60 


-40 


-  20 


L-    0 


L.P.  Cyl. 


ENGINE    No.    84. 

Four-valve  cross  compound,  17y  and  28"  x  48".  Speed, 
100  revolutions  per  minute. 

This  engine  is  a  non-condensing  compound.  The  valves  are 
all  slide  valves,  and  the  steam  and  exhaust  are  operated  by  in- 
dependent eccentrics.  The  diagrams  show  the  effect  produced 
by  changing  the  cut-off  on  the  low-pressure  cylinder,  and  there- 
by the  pressure  in  the  intermediate  receiver.  Diagram  84  a 
was  taken  with  a  receiver  pressure  of  44  Ibs.,  and  diagram 
84  b  with  a  receiver  pressure  of  27|  Ibs.  They  are  all  from  the 
crank  end. 


309 


40- 
30 
20- 
10- 

o- 


30- 

20- 

10- 

O- 


ENGINENo.  84a 


H.P.  Cyl. 


-120 
-100 
—30 
-60 
-40 
-20 
—  0 


L.P.  Cyl. 


ENGINE  No.  84b 


H.P.  Cyl. 


-120 
-100 
-80 
-60 
-40 
-20 
0 


L.P.  Cyl. 


ENGINE   No.  85. 

Four-valve  (Corliss)  cross-compound,  24"  and  34"  x  48". 
Speed,  61  revolutions  per  minute. 

In  this  engine  the  governor  operated  on  the  cut-off  of  the 
high-pressure  cylinder.  The  cut-off  of  the  low-pressure  cylin- 
der was  under  the  control  of  a  pressure  regulator  set  so  as  to 
maintain  a  constant  pressure  in  the  receiver,  irrespective  of  the 
load  or  other  conditions.  Steam  was  withdrawn  from  this 
receiver  for  heating  purposes  ;  in  this  case  for  the  heating  of 
feed- water  for  the  plant  of  boilers  which  supplied  the  engine, 
and  the  diagrams  given  were  taken  under  two  conditions  of 
running ;  first,  No.  85  a,  when  all  the  steam  was  used  for 
power,  and  second,  No.  856,  when  the  steam  was  withdrawn 
from  the  receiver  as  noted. 


311 


ENGINE  No.  85a 


H.P.  Cyl. 


-100 
-80 
-60 
—40 
-20 
-  0 


L.P.  Cyl. 


r I0 

o 

-  0 
—  5 

-  10 


ENGINE  No.  85b 


H.P.  Cyl. 


-100 
-80 
—  60 
-40 
-20 
-  0 


UP.  Cyl. 


-10 

-  5 

-  O 

-  5 
-10 


ENGINE    No.  86. 

Four-valve  cross  compound,  20"  and  36"  x  48".  Speed,  65 
revolutions  per  minute. 

The  condenser  of  this  engine  is  the  siphon  type,  and  the 
injection  water  is  supplied  by  an  independent  direct-acting 
steam  pump.  This  is  arranged  so  as  to  exhaust  into  the 
receiver  or  into  the  condenser,  as  desired.  The  diagrams  given 
were  taken  under  both  of  these  conditions  of  running  the  pump ; 
those  with  the  full  lines  being  taken  when  the  pump  was  ex- 
hausting into  the  receiver,  and  those  with  dotted  lines  when 
the  same  was  turned  into  the  condenser.  The  comparatively 
poor  vacuum  in  the  latter  is  due  to  the  air  leakage  through  the 
packing  around  the  valve  stems  and  piston  rod  of  the  pump. 

ENGINE  No.  86 


H.P.  Cyl. 


L.P.  Cyl. 


—100 

-  80 

-  60 
40 

-  20 

0 

-  15 

-  IO 

-  5 


-    5 


-   10 


313 


ENGINE  No.  87. 

Single-valve  cross  compound,  15"  and  23"  x  15".  Speed, 
260  revolutions  per  minute. 

This  engine  has  unpacked  piston  valves,  one  for  each  cylin- 
der, with  a  shaft  governor  operating  on  the  high-pressure  valve. 

These  diagrams  are  given  to  show  the  effect  of  a  break  in 
the  casting  of  the  high-pressure  steam-chest,  which  allowed 
steam  to  pass  directly  into  the  low-pressure  chest  without  going 
through  the  high-pressure  cylinder.  The  two  cylinders  and  the 
chest  were  all  made  in  one  casting.  Diagrams  No.  87a  and 
876  were  taken  with  a  load  of  79.5  I.  H.  P.,  and  No.  Sic  and 
Sid  with  a  load  of  131.1,  I.  H.  P.  In  the  former  the  low- 
pressure  cylinder  developed  155.2  H.  P.,  and  in  the  latter  141.3 
H.  P.  In  the  former  the  high-pressure  cylinder  produced  a 
resistance  or  negative  power  equivalent  to  75.7  horse-power, 
while  in  the  latter  this  was  reduced  to  10.2  horse-power.  The 
difference  in  these  quantities  gives  the  respective  horse-powers 
as  stated.  In  diagram  87 a  the  upper  line,  which  ordinarily 
is  the  steam  and  expansion  line,  is  here  the  compression  line, 
and  the  lower  line  is  the  one  that  is  made  during  the  admission, 
expansion,  and  release.  The  boiler  pressure  here  is  75  Ibs.,  and 
the  compression  of  the  exhaust  carries  the  back  pressure  up 
to  120  Ibs.  The  point  of  cut-off  takes  place  at  the  very  begin- 
ning of  the  stroke,  and  evidently  there  is  no  steam  admitted 
save  that  which  comes  from  the  compression  of  the  exhaust. 

Diagrams  Sle  and  87/  were  taken  from  an  engine  of  the 
same  size  and  make,  in  which  there  was  no  defect  such  as  that 
mentioned ;  and  a  comparison  with  these  will  show  the  effect 
produced  by  the  disordered  condition.  In  these  diagrams  the 
high-pressure  cylinder  developed  71.4  I.  H.  P.,  and  the  low- 
pressure  53.3,  making  a  total  for  the  engine  of  124.7  I.  H.  P. 
This  is  about  the  same  power  as  that  shown  by  diagrams  Sic 
and  Sid. 

These  diagrams  are  all  from  the  crank  ends. 


314 


ENGINE  No.  87a 


25- 
20- 
15- 
10- 
5- 
0- 
5- 
10- 


20- 
15- 
10- 
5- 
0- 
5- 
10- 


H.P.  Cyl 


100 
80 
60 
40 
20 
-  0 


ENGINE  No.  87b 
L.P.  Cyl, 


ENGINE  No.  87c 
H.P.  Cyl. 


-  40 


20 


"-    0 


ENGINE  No.  87d 
L.P.  Cyl. 


ENGINE  No.  87e 


H.P.  Cyl. 


ENGINE  No.  87f 


L.P.  Cyl. 


-  60 
-40 

-  20 

-  0 


ENGINE    No.  88. 

Marine  triple  expansion  engine,  15",  23",  and  40"  x  30". 
Speed,  83£  revolutions  per  minute. 

These  diagrams  show  the  effect  produced  by  leakage  of  the 
low-pressure  piston.  The  dotted  line  on  the  low-pressure  dia- 
gram is  the  one  taken  when  the  leakage  was  going  on,  and  the 
full  line  the  one  taken  with  a  tight  piston.  The  diagrams  S8a 
from  the  intermediate  and  high-pressure  cylinders  are  those 
taken  with  the  tight  engine.  The  effect  of  stopping  the  leak- 
age, which  was  due  to  the  weakness  of  the  springs  under  the 
packing-rings,  was  to  raise  the  pressure  in  the  receiver.  The 
increase  was  4-lbs.  Another  effect  was  to  increase  the  speed 
of  the  engine  when  running  at  full  capacity  from  81  revolutions 
per  minute  to  84.  Still  another  effect  was  to  increase  the  power 
developed  from  410  I.  H.  P.  to  442  I.  H.  P. 

ENGINE  No.  88a 


H.P.  Cyl. 


140- 
120- 
100- 
80 
60- 
40- 
20- 


ENGINENo.  88b 
L.P.  Cyl. 


5- 
0- 
5- 
10- 


317 


ENGINE   No.   89. 

Compound  high-speed  non-condensing  engine,  6"  and  12"  x 
12".  Speed,  201  revolutions  per  minute. 

These  diagrams  are  given  simply  as  curiosities.  The  high- 
pressure  cylinder  is  doing  nearly  all  the  work,  and  the  condi- 
tions under  which  the  steam  is  distributed  are  about  as  wasteful 
as  could  occur.  There  is  no  cut-off  in  the  high-pressure  cylin- 
der ;  the  terminal  pressure  is  the  highest  of  any  part  of  the 
diagram,  the  release  is  late,  and  the  back  pressure  on  the  low- 
pressure  diagram  is  excessive. 


-60 


—  40 


—  20 


—     0 


L.P.  Cyl. 


-  40 


-   20 


318 


ENGINE    No.    90. 

Diagrams  90  a  and  90  b  are  introduced  partly  as  curiosities 
and  partly  to  show  the  general  features  of  diagrams  obtained 
from  a  steam-driven  air-pump  operating  an  independent  con- 
denser. Here  the  cylinder  was  10"  x  10".  Diagram  90  a  was 
taken  when  the  pump  exhausted  into  the  condenser,  and  dia- 
gram 90  b  when  it  exhausted  into  the  atmosphere.  The  pecu- 
liarity of  these  diagrams  lies  in  the  fact  that  the  pump  takes 
steam  at  full  stroke,  exhausts  at  a  higher  pressure  than  the 
pressure  of  admission ;  and  the  return  stroke  is  made,  for  a  por- 
tion at  least,  under  the  wasteful  conditions  of  a  very  high  back 
pressure.  Another  curiosity  is  the  stopping  of  the  piston  at 
about  the  middle  of  the  stroke,  and  the  rebounding  of  the  same 
before  it  proceeds  on  its  course. 

When  this  pump  was  running  non-condensing  the  exhaust 
steam  was  measured  by  collecting  and  condensing  it  in  a  barrel 
of  water.  It  was  found  to  use  717  Ibs.  of  steam  per  hour,  at  a 
speed  of  61.2  double  strokes  per  minute,  or  103.3  Ibs.  of  steam 
per  I.  H.  P.  per  hour,  the  power  developed  being  6.94  H.  P. 
This  performance  represents,  as  might  be  expected,  a  very 
wasteful  use  of  steam ;  but  it  should  be  stated  that  in  a  plant 
properly  arranged  the  heat  of  the  steam  can  be  utilized  in 
warming  the  feed-water,  and  the  loss  is  reduced  to  a  compara- 
tively small  quantity. 


319 


ENGINE  No.  9Oa 


Head  End 


Crank  End 


ENGINE  No.  9Ob 
Head  End 


Crank  End 


-40 
-20 

0 
10 

-40 
-20 

-  O 

-  10 


-40 


-20 


-   0 


-40 


-20 


STEAM -PIPE   DIAGRAMS. 


321 


STEAM-PIPE   DIAGKAMS. 


THE  effect  which  a  running-engine  has  upon  the  pressure  in 
the  steam  pipe,  as  shown  by  an  indicator  diagram  taken  from 
the  pipe,  is  a  matter  which  not  only  possesses  interest  from  an 
engineering  point  of  view,  but  it  has  a  bearing  on  an  important 
question  relating  to  steam-pipe  design.  The  fluctuations  of 
pressure  in  the  pipe  caused  by  the  intermittent  flow  of  steam 
into  an  automatic  cut-off  engine  is  sufficient  to  set  up  vibrations 
in  the  pipe ;  and  these  extend  from  the  engine  through  the 
whole  distance  back  to  the  boiler  unless  the  pipe  is  well  an- 
chored, and  sometimes  in  spite  of  what  appears  to  be  good 
anchorage.  When  we  consider  the  relatively  small  weight  of 
the  substance  which  is  traveling  through  the  pipe,  it  is  difficult 
to  realize  the  powerful  effect  which  these  fluctuations  have  upon 
its  stability.  It  is  not,  however,  the  substance  itself  which  is 
the  potent  factor  in  the  matter,  but  the  effect  of  the  unbal- 
anced pressure  acting  between  the  two  ends  of  a  section  of  pipe 
produced  by  the  sudden  and  intermittent  reduction  of  pressure 
at  the  end  nearest  the  engine.  If  the  reduction  is  10  Ibs.  and 
the  diameter  of  the  pipe  is  8",  there  is  an  unbalanced  pressure 
of  10  Ibs.  per  square  inch  upon  an  area  of  about  50  square 
inches,  or  a  total  force  of  500  Ibs.  acting  in  the  direction  of  the 
length  of  the  section.  Such  a  force  would  have  in  a  measure 
the  effect  of  a  500  Ib.  blow  upon  the  pipe,  which,  of  course,  is 
a  serious  matter.  These  fluctuations  can  be  overcome  to  some 
extent  by  avoiding  short  right^angle  elbows,  and  employing 
long-turn  bends  in  their  place.  They  can  be  overcome  more 
effectually  by  introducing  in  the  steam  pipe  as  near  as  possible 
to  the  engine  a  reservoir  having  considerable  volume  relative 
to  the  size  of  the  cylinder,  and  passing  the  steam  through  the 
large  space  thus  provided.  The  fluctuations  will  then  occur 

323 


324  ENGINE    TESTS. 

mainly  in  that  part  of  the  pipe  which  lies  between  the  reservoir 
and  the  cylinder,  and  the  reservoir  serves  to  prevent  them  to  a 
large  extent  from  extending  back  to  the  boiler.  The  steam- 
pipe  diagrams  here  given  show  the  desirability  of  employing 
some  means  for  reducing  the  extent  of  these  fluctuations,  and 
in  one  instance  the  beneficial  effect  of  a  reservoir  is  clearly 
revealed. 


ENGINE    No.    91. 


Diagrams  91«  and  916  were  taken  from  a  9"  steam  pipe 
supplying  a  28"  x  48"  Corliss  non-condensing  engine  running 
at  a  speed  of  100  revolutions  per  minute.  The  pipe  is  a 
branch  from  a  long  12"  pipe  leading  to  the  boilers,  and  its 
length  measured  from  the  12"  is  about  30  feet.  The  pipe 
contains  6  short  right-angle  elbows.  Diagram  91#  is  com- 
plete for  the  entire  revolution  of  the  engine,  and  reveals  the 
pulsations  produced  by  the  admission  at  both  ends  of  the 
cylinder.  Diagram  91#  relates  to  one  stroke.  The  indicator 
diagram  from  the  cylinder  taken  on  the  same  stroke  is  also 
shown. 


60- 
40- 

20- 

0- 
80- 

60- 

40- 

20- 

0  — 


ENGINE  No. 91a 


It  will  be  seen  that  just  before  the  beginning  of  the  stroke 
the  pressure  in  the  steam  pipe  drops  ;  and  it  is  maintained  nearly 
constant  until  the  cut-off  takes  place,  when  it  immediately  rises. 

325 


326  ENGINE    TESTS. 

Afterwards  the  pressure  gradually  falls,  and  a  short  time  before 
the  opposite  end  of  the  stroke  is  reached  it  rises  again.  Subse- 
quently when  the  very  end  is  reached  it  falls  abruptly,  co- 
incident with  the  admission  of  steam  to  the  other  end  of  the 
cylinder. 


ENGINE   No.   92. 


Diagrams  92a  and  926  are  from  an  8"  steam  pipe  supply- 
ing a  23"  x  60"  non-condensing  Corliss  engine  running  at 
a  speed  of  75  revolutions  per  minute.  The  pipe  is  82  feet 
in  length,  measured  from  the  nearest  boiler  to  the  throttle 
valve,  and  it  contains  5  short  right-angle  elbows.  Diagram 
92#  applies  to  a  complete  revolution,  and  926  simply  to 
the  forward  stroke  taken  while  the  piston  was  moving  from 


ENGINENo.92a 


-80 
-60 
-40 
-20 

—  0 
-80 

-60 
-40 
-20 
-  0 


the  head  end  of  the  cylinder.  The  indicator  diagram  from  the 
head  end  of  the  cylinder  is  also  given.  Referring  to  the  latter, 
it  appears  that  just  prior  to  the  beginning  of  the  stroke  the 
pressure  rises  in  the  steam  pipe.  Coincident  with  the  move- 
ment of  the  piston  forward  during  the  admission,  the  pressure 
in  the  pipe  gradually  falls  up  to  the  point  of  cut-off,  and  when 
this  occurs  it  rises  to  a  point  some  10  Ibs.  above  the  line  of 

327 


328  ENGINE    TESTS. 

average  pressure.  At  a  point  just  beyond  the  middle  of  the 
stroke  the  pressure  gradually  falls,  until  just  before  the  end 
of  the  forward  stroke  it  suddenly  rises  again  preparatory  to 
the  beginning  of  the  return  stroke. 

This  diagram  is  a  curiosity  for  the  reason  that  the  pressure 
rises  at  the  very  beginning  of  the  stroke,  when  presumably  the 
cylinder  is  taking  steam,  whereas  under  the  ordinary  circum- 
stances it  would  be  expected  that  the  operation  would  be 
reversed  and  the  pressure  would  fall.  The  probability  is  that 
owing  to  the  compression  of  the  exhaust  steam  into  the  clear- 
ance space  the  quantity  of  live  steam  admitted  is  very  small. 

Another  curiosity  in  this  diagram  is  the  fall  of  pressure 
from  the  middle  to  nearly  the  end  of  the  stroke.  During  this 
period  there  is  no  steam  being  drawn  out  of  the  pipe,  and  the 
only  explanation  of  this  action  is  the  assumption  of  a  sort  of 
rebounding  of  the  steam  within  the  pipe  due  to  the  intermit- 
tent character  of  the  flow.  In  this  matter  as  well  as  in  the 
conformation  of  the  diagram  throughout,  there  are  many  points 
which,  to  say  the  least,  are  obscure. 


ENGINE    No.  93. 

This  diagram  is  from  a  1"  pipe  supplying  a  Corliss  con- 
densing engine,  32"  x  54",  making  47  revolutions  per  minute. 
The  engine  diagram  given  is  from  the  crank  end  of  the 
cylinder,  and  the  steam-pipe  diagram  refers  to  one  stroke  of 
the  piston,  that  is,  the  one  made  from  the  crank  end  to  the 
front  end.  This  engine  was  one  cylinder  of  a  pair,  and  the 
steam  pipe  consisted  of  a  10"  main  leading  from  the  boilers 
and  a  7"  branch  to  each  cylinder.  The  distance  from  the 
10"  to  the  throttle  valve  was  20  feet,  and  it  contained  two 
right-angle  elbows.  The  other  cylinder  was  in  operation  when 
the  diagram  was  being  taken. 


80^ 


60  — 


40- 


20- 


o- 

10- 


On  the  steam-pipe  diagram  it  appears  that  the  pressure  rises 
just  before  the  beginning  of  the  stroke,  and  immediately  after 
it  drops  back  to  nearly  the  same  point,  and  remains  nearly  con- 
stant until  the  steam  is  cut  off  from  the  cylinder,  when  it 
rises.  Just  before  the  middle  of  the  stroke  the  pressure  falls 
again,  this  action  being  due  presumably  to  the  other  cylinder 
taking  steam,  followed  by  another  rise  in  the  pressure  at  about 
the  time  of  the  cut-off  in  the  other  cylinder.  Just  prior  to 
the  beginning  of  the  return  stroke  the  pressure  rises  as  before, 
and  again  drops  soon  after  the  beginning  of  the  return  stroke, 
when  the  other  end  of  the  cylinder  begins  to  take  steam. 

329 


330  ENGINE    TESTS. 

Here  is  another  curiosity.  At  the  very  beginning  of  the 
steam-pipe  diagram  the  pressure  increases  in  a  marked  degree 
at  the  time  when  apparently  the  cylinder  begins  to  take  steam, 
and  then  immediately  drops  back.  The  reason  for  this  action 
is  difficult  of  explanation. 


ENGINE    No.   94. 


Diagram  No.  94  is  from  the  steam  pipe  of  the  right-hand 
cylinder  of  a  pair  of  double-valve  engines,  17"  x  24",  running 
at  a  speed  of  154  revolutions  per  minute. 


ENGINE  No.  94 


—60 
-40 
-20 
—  0 


The  main  pipe  here  was  140  feet  in  length,  10"  in  diameter, 
and  had  3  short  right-angle  elbows.  The  branch  pipe  for  the 
two  cylinders  were  each  6"  in  diameter  and  8'  in  length,  and 
each  contained  2  righkangle  elbows.  This  is  the  same  engine 
as  that  referred  to  as  No.  10  in  the  section  on  Feed-Water 
Tests,  but  it  was  taken  with  an  indicator  having  a  different 
scale  from  the  diagrams  given  in  connection  with  the  results 
of  those  tests. 

It  will  be  seen  in  this  diagram  that  the  effect  of  the  closing 
of  the  valves  at  the  points  of  cut-off  are  clearly  revealed,  but 
that  in  other  respects  the  various  operations  are  not  clearly 
defined.  Considering  that  the  reciprocations  are  somewhat 
rapid,  and  that  the  diagram  shows  the  effect  of  the  fluctua- 
tions produced  by  both  cylinders,  it  is  difficult  to  make  a  close 
study  of  its  various  features. 


331 


ENGINE   No.    95. 

Diagram  No.  95  is  from  the  steam  pipe  of  a  20"  x  50"  four 
valve  engine  making  65  revolutions  per  minute. 


-70 
-60 
-50 
-40 
-30 
-20 
-  10 
0 


The  pipe  is  5"  in  diameter  and  36'  long,  and  it  contains  4 
short  right^angle  elbows.  This  is  the  same  engine  as  the  one 
numbered  76  under  the  head  of  Valve  Setting.  The  features 
in  this  diagram  conform  in  the  main  to  what  would  be  expected 
from  the  known  operations  of  the  steam.  The  pressure  drops 
at  the  beginning  of  the  stroke,  and  rises  at  the  point  of  cut- 
off ;  and  when  the  opposite  end  of  the  stroke  is  reached  it  drops 
again,  coincident  with  the  opening  of  the  steam  valve,  and 
rises  again  when  the  cut-off  at  the  other  end  takes  place.  One 
feature  here  is  noticeable ;  and  that  is,  that  the  effect  of  the 
subsequent  admission  after  the  cut-off,  which  is  shown  on  the 
diagram  taken  from  the  cylinder,  the  same  as  in  No.  76,  is 
clearly  revealed  on  the  steam-pipe  diagram,  where  there  is  a 
second  fall  of  pressure  just  beyond  the  point  where  the  rise 
occurs  due  to  the  regular  cut-off.  The  fall  of  pressure  com- 
mencing at  the  middle  of  the  stroke  and  continuing  to  near  the 
end  is  a  feature  of  this  diagram  the  same  as  in  some  of  the 
preceding  ones  which  have  been  referred  to,  though  here  it 
takes  place  more  gradually  than  in  some. 


332 


ENGINE   No.   96. 


Diagrams  96#  and  96&  are  from  the  head  end  of  a  Corliss 
condensing  engine,  20"  x  48"  running  at  a  speed  of  60  rev- 
olutions per  minute. 


100- 

80- 
60- 
40- 
20- 

0 
IOJ 


100- 

80 
60- 
40- 
20- 

0- 

10 


This  engine  is  one  of  a  pair ;  but  when  these  diagrams  were 
taken,  the  second  cylinder  was  out  of  use,  and  the  throttle 
valve  closed.  The  main  pipe  here  is  10"  in  diameter  and  33' 
in  length.  The  branches  are  6"  in  diameter,  and  the  one  lead- 
ing to  the  left-hand  cylinder  is  10'  in  length,  and  that  to  the 
right-hand  cylinder  15'  in  length.  Each  of  these  branches 
has  two  short  right-angle  elbows.  The  diagrams  were  taken 
from  the  left-hand  cylinder.  Diagram  96a  was  taken  when  the 
steam  was  passing  through  the  pipe  above  referred  to.  When 

333 


334  ENGINE    TESTS. 

diagram  965  was  taken  the  10"  pipe  was  shut  off  at  the  boiler 
end,  and  steam  was  furnished  through  twenty-five  feet  of  8"  pipe 
and  one  45  degree  elbow  into  a  tee  at  the  boiler  end  of  the  10" 
main.  In  both  these  diagrams  the  admission  of  steam  is  accom- 
panied by  a  drop  of  pressure  in  the  pipe,  as  would  be  expected, 
and  a  corresponding  rise  of  pressure  at  the  point  of  cut-off.  In 
diagram  96a  the  pressure  falls  again  very  quickly  after  cut-off ; 
and  a  succession  of  wavy  lines  occur  until  the  middle  of  the 
stroke,  and  then  the  pressure  is  nearly  constant  to  the  end.  In 
diagram  96£,  on  the  contrary,  the  fall  of  pressure  just  after  the 
cut-off  is  much  less  marked,  and  there  is  considerable  more  rise 
in  pressure  as  the  end  of  the  stroke  is  approached.  The  only 
difference  in  the  conditions  under  which  these  diagrams  were 
obtained  was  in  the  lengthened  pipe  through  which  the  steam 
passed.  It  would  seem,  therefore,  that  the  arrangement  of  the 
pipe  has  much  to  do  with  the  character  of  the  fluctuations. 
It  will  be  noticed  also  in  these  diagrams  that  the  fluctua- 
tions resemble  in  some  respects  those  which  occur  on  previ- 
ous diagrams  taken  from  a  pair  of  engines  with  both  cylin- 
ders running.  In  this  case,  however,  only  one  cylinder  was 
in  operation.  Here  is  another  indication  that  the  arrangement 
of  the  pipe  has  much  more  effect  upon  the  character  of  the 
fluctuations  than  would  at  first  be  supposed. 


ENGINE   No.   97. 

Diagram  No.  97  is  from  a  10"  steam  pipe  supplying  a  SO'' 
x  72"  Corliss  engine,   making  60  revolutions  per  minute. 


ENGINE  No.  97 


-80 


-60 


-40 


-20 


—  0 

-   10 


The  steam  pipe  is  108  feet  in  length  from  the  main  header 
in  the  boiler-room,  and  it  contains  five  short  right-angle  elbows. 
The  fluctuations  of  pressure  here  are  of  much  less  extent  than 
in  any  of  the  preceding  diagrams,  due  in  part  probably  to  the 
relatively  light  load  on  the  engine.  In  view  of  what  the  pre- 
ceding diagrams  have  shown,  the  real  cause  of  so  little  variation 
may  be  some  peculiar  arrangement  of  the  pipes  which  acted 
favorably. 


335 


ENGINE    No.  98. 


Diagram  No.  98  is  taken  from  an  8"  steam  pipe  supplying 
a  24"  x  48"  Corliss  engine  running  at  a  speed  of  62  rev- 
olutions per  minute. 


-100 
-80 
-60 
-40 
-20 

-  0 

-  10 


The  pipe  is  135  feet  in  length,  and  contains  5  short  right- 
angle  elbows  and  two  45  degree  elbows.  The  lines  in  this 
diagram  are  very  clearly  marked.  There  is  a  sudden  drop  in 
the  pressure  just  at  the  beginning  of  the  stroke,  and  there  is  a 
marked  rise  of  pressure  at  the  point  of  cut-off.  There  seems  to 
be  little  variation  of  pressure  after  this  time  until  nearly  the 
end  of  the  stroke.  During  the  very  last  part  of  the  stroke, 
however,  the  pressure  drops  the  same  as  noticed  in  many  of  the 
preceding  diagrams,  although  there  appears  to  be  no  action  in 
the  working  of  the  steam  in  the  cylinder  that  should  cause  it. 
This  is  one  of  the  things  that  makes  the  reasons  for  the  par- 
ticular conformation  of  steam-pipe  diagrams  obscure. 


ENGINE    No.  99. 


Diagram  No.  99  was  taken  from  a  6"  pipe  supplying  a  14" 
and  26"  x  42"  compound  engine  running  at  a  speed  of  100 
revolutions  per  minute. 


-'40 

-120 

-100 
80 

-  60 
—  40 

-  20 

0 


The  length  of  the  pipe  was  75  feet,  and  it  contained  two 
short  right-angle  elbows.  Here  is  another  case  where  the  lines 
of  the  diagram  are  clearly  marked,  and  there  can  be  no  miscon- 
ception in  regard  to  the  action  going  on  in  the  pipe.  This  dia- 
gram is  similar  to  the  one  which  precedes  it,  and  has  the  same 
general  features.  There  is  this  peculiarity,  however,  that  there 
is  practically  no  drop  of  pressure  during  the  period  of  admis- 
sion. The  drop  occurs  toward  the  very  end  of  the  previous 
stroke.  Subsequent  to  the  cut>off  and  prior  to  this  drop,  the 
pressure  is  well  nigh  constant.  The  indicator  diagram  here 
given  is  from  the  head  end,  and  refers  simply  to  the  high- 
pressure  cylinder. 


337 


ENGINE    No.    100. 

Diagram  No.  100  refers  to  a  case  where  a  reservoir  was 
installed  in  the  steam  -pipe  close  to  the  cylinder,  and  the  dia- 
gram was  taken  from  this  reservoir.  The  engine  is  a  Corliss 
30"  x  48",  running  at  a  speed  of  80  revolutions  per  minute. 
The  receiver  is  supplied  from  an  8"  pipe  223  feet  in  length, 
which  contained  six  short  right-angle  bends,  while  the  engine 
is  supplied  from  the  reservoir  through  a  10"  pipe  12"  long, 
containing  two  short  right-angle  elbows.  The  size  of  the 
reservoir  is  42"  in  diameter  and  8'  in  height. 


roo- 

80- 
60- 
40 
20 

0- 
10- 


ENGINENo.  100 


In  this  diagram  the  fluctuations  of  pressure  do  not  seem  to 
follow  the  admission  and  cutting  off  of  the  steam  to  any  great 
extent,  and  at  the  worst  they  are  confined  within  narrow  limits. 
The  extreme  change  of  pressure  from  the  highest  to  the  lowest 
is  three  pounds.  Comparing  this  with  the  previous  instance, 
No.  99,  the  difference  is  exceedingly  marked.  There  the  change 
of  pressure  was  some  thirteen  pounds.  If  we  investigate  these 
two  cases  carefully  it  will  be  found  that  the  rate  of  flow  of 
steam  from  the  boiler  to  the  reservoir  is  forty-three  feet  per 
second,  and  in  the  other  case  (No.  99)  the  rate  of  flow  close  to 
the  throttle  valve  was  twenty-eight  feet  per  second.  The  con- 
ditions as  to  the  speed  of  the  steam  and  the  quantity  with- 
drawn per  stroke  with  reference  to  the  size  of  the  pipe  was 


ENGINE   No.  100.  339 

therefore  much  more  severe  in  the  case  where  the  reservoir  was 
used.  It  thus  appears  that  with  the  same  conditions  of  service, 
the  favorable  effect  produced  by  the  reservoir  would  have  been 
even  greater  than  that  here  indicated. 


.WfrUMT/?,. 

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